by William M. Kelly
Chapter 3: Crushed Stone
The use of crushed stone for construction projects has a long history in New York. The State Geologist, Frederick Merrill, reported in 1895 that crushed stone was the material of choice for making durable roads of good quality. At that time, trap rock, granite sensu lato, and metamorphic rock, limestone, sandstone, and shale were used for road metal. Merrill noted that limestone was the best material as the fine-grained detritus produced in the crushing process acted like mortar when placed on a road surface. Igneous and metamorphic rocks did not produce cohesive fines and were less favored. He also noted that if these rocks were micaceous, they disintegrated rapidly. Shale was to be avoided except for local, light-duty roads. Sand and gravel were relegated to base layers (Merrill 1895). The production and use of crushed stone grew as New York’s economy expanded. While the total amount of stone quarried in New York remained relatively constant, the advent of concrete use for building and construction projects caused the amount of dimension stone produced in New York to decrease while crushed stone tonnage increased. By the 1920s, crushed stone accounted for 50 percent of the total value of stone produced in the state (Newland 1921).
In the late nineteenth century, small crushed stone operations were widespread in New York. Often, the stone to be crushed was stripping waste that was produced as a quarry was developed for another resource. However, even at that time there were some larger quarries established specifically for the production of crushed stone (Merrill 1895). Trap rock (diabase) from the Palisades in Rockland County was quarried in large quantities. Dolostone from quarries farther north on the Hudson River provided what was then recognized as a superior product for road surfaces. Quarries in the Hudson Highlands (e.g., Iona Island) were established to feed the construction and concrete industries; the fine residue from the crushing process was sold as polishing compound. One of the largest quarries in the state at the time was located in South Bethlehem, Albany County. Dedicated crushed stone quarries existed west of Albany in Schoharie County.
As noted above, several types of stone were used for crushed stone in the past. That is also true currently. In the past, materials used for making roads varied locally. If a road was intended for light to moderate traffic, local stone, whatever it consisted of, could safely be used. Shale was an exception to this rule. However, if traffic was anticipated to be heavy, use of high-quality aggregate was economically warranted. Unfortunately, rocks that produce good-quality crushed stone are not evenly distributed geographically in New York and this results in the necessity to import suitable stone.
At present, several types of rock can be used for crushed stone in New York. These included igneous rocks such as diabase (trap) and granite; metamorphic rocks such as gneiss and marble; and sedimentary rocks, most prominently represented by limestone, dolostone, and sandstone. Figure 11 shows the distribution of rocks that can be quarried for crushed stone that will meet modern quality specifications. In practice, igneous rock is rarely used for crushed stone as little of this rock type exists in New York. Trap rock is only quarried from the diabase sill in Rockland County and there is little unmetamorphosed granite in New York.
Map of rocks suitable for crushed stone. (Source: NYS Department of Transportation, 2010.)
However, rocks of high metamorphic grade are abundant in the Adirondacks and in the Hudson Highlands and Manhattan Prong of southeastern New York. Commonly, what is called crushed “granite” is in fact metamorphic rock such as granitic gneiss. The mineralogical composition of these rocks is variable in terms of modal percent quartz, plagioclase, and K-feldspar. So strictly speaking geologically, the rocks are meta-granite, meta-syenite, meta-quartz diorite, and so on. Some marble units and calc-silicate rock produce acceptable-quality aggregate. Perhaps surprisingly, a micaceous pelitic gneiss is the source of crushed stone at a quarry in Dutchess County.
Among the sedimentary rocks, sandstone and carbonate units produce suitable stone. Within the realm of carbonate rocks, all other properties being equal, the amount of noncarbonate minerals present, expressed as acid insoluble residue (AIR), can affect the final use of the product. Rock units with low values of AIR may not be suitable for use in the top layer, the friction surface, of certain roads. If this is the case, high-friction aggregate can be blended in or the rock can be used for other purposes (e.g., base layers), where polishing of the aggregate is not an issue.
A mineral resource can only be mined where it exists, and it is clear from Figure 11 that there are large areas of New York that are not underlain by rock which qualifies for use as crushed stone. Furthermore, Figure 11 is a generalization that overestimates the amount of quarryable stone. Not all of the rock in the regions highlighted is suitable for aggregate production. For instance, large parts of Broome, Delaware, Sullivan, and Ulster counties are shown as potential sources of sandstone. However, while good-quality sandstone does exist in that area, a large portion, perhaps half, of the bedrock in the region is shale interbedded with the sandstone; shale has no utility for construction aggregate. Similarly, the Adirondack region and the Hudson Highlands, shown as metamorphic rock in Figure 11, do contain rocks that produce acceptable crushed stone. But again much of the rock in those regions is comprised of micaceous schist, charnokite, and gneiss that will not make tough, durable aggregate. Furthermore, just as is the case with sand and gravel deposits, environmental concerns, existing residential or commercial buildings, infrastructure, park lands, and so on, all restrict the access to the resources that is actually available for development.
Development of a modern quarry and production facility for construction aggregates is a complex process. New plant construction can take up to six years for planning, design, site preparation, and construction. If a “greenfield” site is chosen for the facility, diamond drilling is done to extract core of the bedrock. The core is used to determine the quality and the quantity of the stone available. This information is used to guide the overall mining plan. If the site is forested, the trees must be logged and removed. The overburden, soil and unusable rock, is then stripped off the proposed quarry site. Soil is typically retained for reclamation purposes, depending on the final disposition of the site. A large amount of material must often be removed from the site in order to establish a new facility. In 2009, 600,000 cubic yards of “mud” and 3 million tons of rock were removed to build a new plant in Rockland County (Maio 2009).
Location of mining faces and face height, if the rock is homogeneous, is based on permitted limits and the most economical setbacks and slope angles to maximize the use of the reserves. Typical face height varies from 6 to 9 meters (20 to 30 feet) to 18 to 21 meters (60 to 70 feet). Face height and location may depend upon selective quarrying needed to meet NYS Department of Transportation requirements for the quality of the aggregate.
To separate the rock from the quarry face, the rock is drilled and blasted. Blast hole drilling is accomplished by track-mounted or truck-mounted percussion rotary air blast drills. In general, at larger operations and where the terrain is level, a truck-mounted drill is used. In smaller operations, or where the ground is uneven or sloped, track-mounted equipment is used. Hammer-type drills are used for this procedure. Technologically newer down-the-hole drills have a percussion mechanism, with the “hammer” located just behind the drill bit. Impact from the hammer strikes the bit directly so no energy is lost at the joints of the drill stem and the percussion casing provides stability to the drill bit. This produces a straighter hole, that is drilled more quietly. Older drills have the percussion mechanism mounted at the top of the drill mast so that the impact energy has to travel through the entire drill string to reach the bit.
Blasting can be done using either contracted or in-house personnel. In New York, the most commonly used explosive agents are a mixture of ammonium nitrate and fuel oil (ANFO) or emulsions (an immiscible water-in-oil mixture of ANFO and additives, the latter serving to boost the energy of the explosion and provide water resistance). Emulsions are often used where water may be encountered in the blast hole or in the rock. Both types of blasting agents are generally pumped into the blast holes from a bulk truck as a flowable material. Cartridge-type explosives are used in specialized situations. Typically, a booster explosive will be placed at the bottom of the hole, which will be ignited by a detonator. Nonelectric detonators are currently more commonly used than electronic detonators. Electronic detonators are used in specialized situations such as unusual rock face configurations, proximity to neighbors, or problems with rock breakage.
Blast vibration monitoring can also be either contracted or accomplished in-house. Often, ground vibrations at the property perimeter and/or more remote locations are recorded when new mining operations are established. In some cases, permanent monitoring stations are established on neighboring properties. NYSDEC mining permits require that all blasts be monitored with at least one properly calibrated seismometer. Additional seismometers are used if site-specific conditions warrant. The ground vibration caused by blasting is measured in terms of peak particle velocity (ppv). At present, New York standards are based upon guidelines researched and designed by the U.S. Bureau of Mines to prevent even cosmetic damage to the weakest building materials (Siskind et al. 1980). The U.S. Bureau of Mines research indicated that the maximum allowable ground vibration that would prevent any damage varied, dependent on the frequency. At frequencies above 40 hertz, the allowable peak particle velocity is capped at 2.0 inches per second (ips). The allowable ppv is capped at 0.75 ips for mid-range frequencies at typically newer homes containing dry wall interior, and at 0.50 ips for mid-range frequencies for older homes containing plaster interior. The allowable ppv is variable for very low frequencies (see Figure 12).
USBM Ground Vibration Guidelines. (Siskind et al. 1980.)
The U.S. Bureau of Mines guidelines (Siskind 1980a) for air overpressure (or air blast), the blast-induced vibrations that travel through the air, have also been adopted in New York. These standards prevent damage to the building material most susceptible to air overpressure: glass in a poorly installed window. These limits vary depending on the type of measuring system:
|Measuring System||Maximum Air Overpressure|
|0.1 Hz High Pass||134 dB Align|
|2.0 Hz High Pass||133 dB|
|5 or 6 Hz High Pass||129 dB|
|C Slow (Not Exceeding 2 seconds)||105 dB|
Most commercially available seismographs use a 2.0 Hz high pass system.
Commonly, there are misconceptions about blasting and the damage caused by the resulting ground vibration. When questioned, most people believe that the louder the noise caused by the air overpressure, the greater the potential damage caused by the ground vibration. There is not necessarily a relationship between the two. The human body is very sensitive to blasting. Research has shown that an observer experiencing a mine blast accompanied by loud noise is likely to judge the ground vibration to be very strong, and therefore to suspect structural damage, at a ppv level of one tenth to one hundredth of that needed to damage a structure (Hemphill 1981).
Quarry blasts typically liberate between 10,000 and 15,000 and between 70,000 and 100,000 tons of material. The size of the blast and layout of the shot pattern must take the geology, structure, and weaknesses in the rock (mud seams), and neighboring properties, into account. A typical crushed stone quarry is shown in Figures 13 and 14. The blasted material is loaded into haul trucks (Figure 15) to be transported to a fixed or movable crusher (Figures 16a, 16b), but it is not uncommon for “load and carry” procedures to be used. Trucks vary in capacity, dependent on the needs of each operation, but typically range from 30 to 35 tons to 75 tons with about 50 tons capacity being the average. The crushed product is screened and stockpiled (Figure 17).
Typical crushed stone quarry. Dolostone units mined here are typically the Tribes Hill Formation. (Courtesy Callanan Industries, Inc.)
Quarry face in a carbonate rock quarry. The geological formations are nearly horizontal. (Courtesy Callanan Industries, Inc.)
Wheeled loading and hauling equipment is used to move blasted rock to the crushing plant. (Courtesy Callanan Industries, Inc.)
Truckload of blasted rock at primary crusher. (Courtesy Callanan Industries, Inc.)
Truckload of blasted rock at primary crusher. (Courtesy Callanan Industries, Inc.)
Truckload of blasted rock at primary crusher. (Courtesy Callanan Industries, Inc.)
Products and UsesThe term “crushed stone” is applied to rock that has been broken into small, irregular fragments of specific particle size (Table 4). In 2006, 52,100,000 metric tons of crushed stone were used in New York (USGS 2006). Due to the economic downturn of the past two years, the 2008 total production of crushed stone was about 43,852,000 metric tons (Table 5). The material is used in metallurgical and agricultural operations, but by far, the majority of crushed stone used in New York is consumed by the construction industry. It can be used without a cement or bitumen binder or it can be mixed with a binding substance such as asphalt or portland cement. Unbound materials are used for a variety of purposes including road base, road surfacing, railroad ballast, or filter stone. Bound crushed stone is used in concrete and black top for road construction and repair, airports, dams, sewers, and residential and commercial foundations (Tepordei 1985).
Information about companies that produce crushed stone in New York is published by the New York State Department of Environmental Conservation, Division of Mineral Resources. Data organized by commodity is available in electronic format at http://www.dec.ny.gov/cfmx/extapps/MinedLand/standard/commodities. More specific information is available in a searchable mines database available at http://www.dec.ny.gov/cfmx/extapps/MinedLand/search/mines.
Table 4. Definitions and Specifications of Selected Aggregate Products. (Source: New York State Department of Transportation 2008.)
Crushed Stone Production in New York. (Source: USGS 2008.)
Many geological formations in New York that can be used as a source for crushed stone have been mapped and adequately described in the past century. As a result, exploration for and development of new mines will most likely occur in one of the known formations. However, as has been shown, geological materials suitable for good-quality crushed stone are not uniformly distributed in the state. It will be necessary to continue to transport certain products ( e.g., concrete sand or high-friction aggregate) from one part of New York to another, or import the material from out-of-state. Furthermore, the environmental and land-use issues that affect sand and gravel mines also impact the crushed stone industry.
It is very important that there be planning, at the state and local levels, for future mineral resources of all kinds, but specifically for construction aggregates. These geological materials directly support the physical infrastructure and economic development of New York’s communities. Zoning and land-use planning can effectively direct most industrial operations into areas reserved for such activities. Preserving these resources for sustainable growth will require that the rocks be identified, characterized for suitability and, in the best case, protected from uses that would prohibit mining.
Details regarding the chemical and physical properties of crushed stone products to be used in New York are specified by the New York State Department of Transportation, Standard Specifications (New York State Department of Transportation 2008). The following generalized description of quality requirements for construction aggregates is derived from Herrick (1994). Stone to be used for aggregates should have a tendency to break into equant, roughly cubic particles with a minimum of flat and elongated shapes. Important physical properties for crushed stone are strength, porosity, and the ability to resist volumetric change in freeze/thaw conditions. Fine-grained rocks tend to be stronger and more abrasion resistant. Tightly interlocking grains produce the best aggregates.
Well-cemented sedimentary rocks, often found in older geologic formations, yield acceptable aggregate. High clay-content rocks, such as shale, produce crushed stone dominated by flat, elongated fragments. Furthermore, these rocks will often disintegrate when subjected to repeated freezing/thawing or wet/dry cycles and hence are unacceptable. Clay content may also make dolomitic rocks unsound. The presence of easily weathered minerals such as feldspars, ferromagnesian silicates, and sulfides can be deleterious.
Rocks to be used for construction aggregates should be chemically inert. Rocks containing silica in the form of chert or chalcedony may react with highly alkaline cement and cause concrete to deteriorate. Certain carbonate rocks in New York, for example, the Onondaga Formation, contain abundant chert. Dolomitic limestone with moderate to high clay content also is not acceptable due to potential microfracturing caused by chemical reaction between the aggregate and the cement. Iron sulfide minerals in aggregate will react to form hydroxides and sulfates and can be deleterious if present in excessive amounts. The minerals pyrite and marcasite are very common in some of New York’s limestone and dolostone. Breakdown of these minerals, when present in concrete, can lead to discoloration and also to expansion and weakening of the mix. Aggregate rich in quartz can have high negative surface charge on the particles that causes bituminous cements to separate from the aggregate. Water can penetrate between the aggregate particle and the binder, causing separation (stripping) and failure of blacktop mixes. Quartzite, along with some granite and high-grade metamorphic rocks can have this effect. However, chemical additives can mitigate the problem.
In some cases, unusual chemical properties of New York rocks can increase their utility and market value. Chemically pure forms of carbonate rocks can be used for chemical stone, flue gas scrubber, and cement. Stone for filters and flue gas scrubbers call for CaCO3 content of 90 percent or greater. That used for cement requires limestone with low (<4%) MgO and low total Na2O and K2O. For example, in central New York, the Jamesville Member of the Manlius Formation and the Edgecliff Member of the Onondaga Limestone are chemically suited for use in the Solvay process for the production of soda ash. Limestone, which can be used for flue gas desulphurization, can be quarried from the Chamont Limestone of the Black River Group in northwestern New York. The Beacraft, Manlius, and Coeymans Formations of the Helderberg Group have long been a raw material source for the manufacture of cement.
Carbonate rocks are the most commonly used for construction aggregates in New York. These rocks are generally found statewide with some notable exceptions. The generalized distribution of carbonate rocks in New York is shown on Figure 18. Statewide, the youngest carbonate units have the simplest distribution patterns. These strata, and the noncarbonates with which they are interlayered, are nearly flat-lying but generally dip slightly to the south and west. In central and western New York, the carbonate rocks are exposed in east–west trending outcrop belts. Along the Hudson River in eastern New York, carbonate rocks crop out in belts that trend north to south. No carbonates are exposed in the Southern Tier of counties along the Pennsylvania border. Sandstone and shale conceal the limestone and dolostone in this area.
Distribution of carbonate rock in New York.
The youngest carbonate unit in New York is limestone of the Middle to Late Devonian Tully Formation. It is exposed to the north of the Pennsylvania border in central New York. Its outcrop belt trends east–west. Eastward, where rocks of equivalent age are exposed, the Tully Limestone is completely replaced by shale and sandstone units. North of the Tully outcrop belt (and stratigraphically older rocks) are the Middle Devonian Hamilton Group, Middle Devonian Onondaga Formation, Early Devonian Onondaga Formation, the Early Devonian Helderberg Group, and the uppermost Silurian carbonates. These units are exposed in parallel east–west outcrop belts. These carbonate units extend to Albany County where the units change orientation to become north–south trending outcrop belts immediately to the west of the Hudson River. The rocks extend from there southward into New Jersey. The outcrop pattern of the oldest and northernmost carbonate unit exposed in central and western New York, the Lockport Group, trends east–west only and disappears near Utica.
Older Late Cambrian and Early Ordovician carbonate rocks underlie the carbonate units exposed in central and western New York and also form north–south trending outcrop belts in eastern New York. Uplifts of the Adirondack Dome and the Frontenac Arch have been sufficient to expose the older carbonates on the flanks of these areas. Outcrop patterns of carbonate units outcropping around the dome and arch reflect the structural complexity of the areas and the limited lateral extent of some of the units.
In the Hudson Highlands of southeast New York, Lower Cambrian quartzite and Middle Cambrian–Upper Ordovician carbonate strata are exposed. Tectonism imparted a northeast–southwest trend to the outcrop patterns of these carbonate rocks. The irregularity of the carbonate outcrop pattern reflects the extensive folding and faulting of the strata. All of the carbonate rocks described below are being, or have been recently, used for aggregate resources in New York.
Carbonate Rock Resources
The Tully limestone crops out in the Finger Lake region of central and western New York from Canandaigua Lake in Ontario County eastward to the Chenango River Valley in Chenango County. Heckel (1973) subdivided the Tully into two members, Upper and Lower. The Lower Member extends only as far eastward as the east branch of the Tioghnioga Valley between DeRuyter and Sheds in Madison County, where it is truncated by the Upper Member. Farther east in the Chenango River Valley, the Upper Member is replaced by shale and sandstone. Heckel (1973) described the Tully as a well-bedded, hard, dense, medium-gray to light-gray fine-grained limestone. The uppermost part of the Tully from Cayuga Lake eastward is interbedded with black shale and is transitional with the overlying shale. To the east of the Skaneateles Lake area, the Tully becomes progressively more sandy and shaley to the exclusion of the carbonate rock. The Tully averages 7 meters (22 feet) in thickness. Locally it exceeds 10.7 meters (35 feet). The Tully thins laterally, disappearing westward and thinning to 7 feet in its last exposure to the east.
The lower Middle Devonian Onondaga is a very widespread unit in New York. The limestone extends from Illinois eastward through New York and southward into Tennessee. In New York, it crops out from the Buffalo to the Helderberg region in Albany County where its outcrop belt sharply changes orientation and extends southward to Kingston and then southwestward to enter New Jersey near Port Jervis. Oliver (1954, 1956) was able to distinguish four members of the Onondaga based upon fossil content and lithology. The members are from oldest to youngest: Edgecliff, Nedrow, Morehouse, and Seneca. Chert is very abundant in some of the strata above the Edgecliff and below the Nedrow in the western part of the state. Ozol (1963) designated the strata in this interval as the so-called Clarence Member of the Onondaga. The fossil content, lithology, and the gamma-ray pattern recorded in wells (Rickard 1975) indicate that the Clarence is a chert-rich facies referable to the Edgecliff. Lindholm (1967) subdivided the Onondaga in the Buffalo to Albany County area based on lithology and fossil abundance. There is little correspondence between the subdivisions of Oliver and those of Lindholm. The relationship between Lindholm's lithofacies and the members of Oliver and Ozol is shown in Lindholm (1967). There has been no attempt here to reassign the named members to the lithofacies of Lindholm (1967).
The Onondaga limestone is to various degrees chert-bearing throughout, although the stratigraphic position of the chert-rich horizons and the overall abundance of chert varies. The unit is mostly fine-grained limestone except for the lower part, which is coarse-grained and composed predominantly of fossils. From the area south of Utica and west to Geneva, the middle of the unit contains more clay and dolostone than elsewhere. Near Syracuse in Onondaga County the Onondaga limestone is about 21 meters (70 feet) thick. Its thickness increases both to the west and to the east—reaching nearly 46 meters (150 feet) in thickness in the Buffalo area, about 33 meters (110 feet) in Albany County, greater than 49 meters (160 feet) near Kingston, and an estimated 61 meters (200 feet) near Port Jervis.
Edgecliff Member, Onondaga Formation
The Edgecliff Member is present throughout the outcrop belt of the Onondaga Formation in New York. Oliver (1954) describes the Edgecliff in the central part of the state as a massive, light-gray to pink, very coarsely crystalline limestone, characterized by a profusion of tabulates, large rugose corals, and crinoid columnals. This unit is locally a coral biostrome, largely made up of coral skeletons in a matrix of crinoid debris. Bioherms up to several hundred feet across occur in this unit. Chert is generally sparse throughout the Edgecliff and is mostly confined to the upper part of the unit, though it may occur throughout (Oliver 1954, 1956).
The Edgecliff becomes finer-grained and darker-colored both to the west and to the east of the Syracuse area. South of Albany County, the lithology of the Edgecliff changes markedly. The coral fauna is sparser and the limestone is darker-colored and more fine-grained. It is distinguishable from the overlying Nedrow and Morehouse only by the presence of large crinoid columnals, which are characteristic of the Edgecliff everywhere (Oliver 1956). The Edgecliff is about 3 meters (8 feet) thick in the Syracuse area. Westward, near Buffalo, it is 1 to 5 meters (3 to 15 feet) thick with locally thicker reef areas. To the east of Syracuse, the Edgecliff thickens to 8 to 9 meters (25 to 30 feet) at Clockville, Oriskany Falls, and Cobleskill and up to 21 meters (70 feet) locally in reef areas. To the south of Albany County the unit thins to 5 meters (15 feet) at Warwarsing and may be as thin as 2 meters (6 feet) near Port Jervis at the New Jersey border.
Nedrow Member, Onondaga Formation
The Nedrow Member crops out from the Buffalo area east to Albany County and south to Kingston. It is not present between the Edgecliff and Morehouse Members at Warwarsing, 22 miles southwest of Kingston. In the Syracuse area, the Nedrow Member is characterized by its slightly argillaceous nature and the species of gastropod fossils it contains. It consists of a lower thin-bedded, argillaceous interval and more sparsely fossiliferous upper part in this area. Chert is relatively uncommon throughout. To the west, at Oaks Corners, and to some degree at Honeoye Falls, the Nedrow is overall lithologically similar to the argillaceous lower part in the Syracuse region (Ozol 1963). The Nedrow is not so argillaceous in the Syracuse area as to prevent its use as aggregate. At Oaks Corners and other locations, the Nedrow is too argillaceous to be used in some aggregate applications. West of these localities neither the distinctive lithology nor fossils occur and it is difficult to distinguish the Nedrow from the overlying Morehouse and the underlying “Clarence Member.” To the east of Syracuse, the Nedrow is less argillaceous and coarser-grained. Its lithology is so similar to the underlying Edgecliff in the Helderberg region of Albany County that only its fossils distinguish it (Oliver 1956). At Leeds and at Kingston, the Nedrow is a light-colored, coarse-grained, cherty limestone distinguishable only by its gastropod fauna (Oliver 1956). The Nedrow is 3 to 5 meters (10 to 15 feet) thick in the Syracuse area and about 13 meters (40 feet) thick in the Buffalo area. It is 5 meters (15 feet) thick in the Helderberg region and thickens considerably to 13 meters (43 feet) at Leeds. Southward it thins further to an estimated 10 meters (34 feet) at Saugerties and pinches out to the south-southwest between Kingston and Warwarsing.
Morehouse Member, Onondaga Formation
The Morehouse Member is present along the entire outcrop belt of the Onondaga Formation in New York from Buffalo east to Albany County and south to the New Jersey border. On the edge of Morehouse Flats near Syracuse, the Morehouse Member is a medium-gray, fine-grained limestone with dark-gray chert that is particularly abundant in the upper part (Oliver 1954). Fossils are very abundant in the upper part, and the Morehouse Member is generally characterized by their variety. Both to the west and to the east the Morehouse thickens considerably and is coarser-grained. To the west, chert is more evenly distributed throughout the member. Chert diminishes in the upper and lower portions of this member until the member can be divided into a non-cherty lower part, a cherty middle part, and a non-cherty upper part. The Morehouse is darker- colored and finer-grained to the south of the Albany County. The tripartite lithologic subdivisions are valid as far as the Kingston area although the uppermost unit is not exposed there (Oliver 1956). The Morehouse is poorly exposed between Kingston and the New Jersey border. Where it is exposed, there is very little chert present.
The Morehouse is 6 to 7 meters (20 to 24 feet) thick in the Syracuse area. Westerly, its thickness increases to 18 meters (60 feet) at Phelps, and it maintains this thickness into the Buffalo area. To the east of Syracuse, the Morehouse is about 21 meters (70 feet) in thickness at Cobleskill and in the Albany area. It increases to over 30 meters (100 feet) at Saugerties, and is estimated at 60 meters (190 feet) at Port Jervis on the New Jersey border.
Seneca Member, Onondaga Formation
The Seneca Member extends from the Buffalo area east to Cherry Valley, southeast of Utica. Lithologically, the Seneca is nearly identical to the Morehouse ( i.e., medium-gray, fine-grained limestones with dark-gray chert and abundant fossils). The fossils, however, are distinctive. The Seneca contains abundant brachiopods (Chonetes lineatus). Beds up to several feet in thickness are composed almost entirely of these shells. Stratigraphically upward, the Seneca is progressively darker-colored and thinner-bedded. At the top it is argillaceous and is interbedded in a gradational contact with the Union Springs Shale (Oliver 1954).
The lithology and fossil content of the Seneca remains constant as far west as Canandaigua Lake. In the Buffalo area, the Seneca is even less distinctive. The presence of the Tioga bentonite at the base is used to distinguish it from the Morehouse (Oliver 1954). Little of the Seneca member is exposed in the quarries in the Buffalo area and the lithology is poorly known. To the east of Seneca County, the Seneca Member retains its lithological characteristics, although progressively more beds are missing from the top. East of Cherry Valley, no Seneca remains in the section (Oliver 1954). The Seneca Member is 6 to 7 meters (20 to 25 feet) thick from the Buffalo area to central New York. Eastward, it thins and at its last appearance near the village of Cherry Valley, the Seneca has a thickness of 2 meters (6 feet).
The outcrop belt of the Lower Devonian Helderberg Group strata parallels that of the overlying Onondaga Limestone from the New Jersey state line to the Finger Lake region. The Helderberg carbonate units thin and disappear at an upper unconformity near Geneva, west of Cayuga Lake between Fayette and Oaks Corners. Only the lowermost Helderberg carbonate formations (Rondout and Manlius) span the entire outcrop belt. The strata above (Coeymans, Kalkberg, etc.) are restricted to the eastern and southeastern part of the state. The subdivisions of the Helderberg carbonates are, from oldest to youngest: the Rondout, Manlius, Coeymans, Kalkberg, New Scotland, Becraft, Alsen, and the Port Ewen Formations. The Helderberg Group is primarily limestone. The Rondout Formation is the only dolostone. The Manlius and Coeymans, and especially the Becraft Formation, are relatively pure limestone. The Kalkberg and Alsen are locally cherty and the New Scotland and the Port Ewen Formations are argillaceous to very argillaceous. In the Helderberg region of Albany County, the Helderberg Group is 68 to 76 meters (225 to 250 feet) thick. It thins to the west as follows: 61 meters (200 feet) thick south of Utica, 41 meters (135 feet) near Syracuse, 20 meters (65 feet) at Union Springs, and disappears west of Cayuga Lake. To the south of the Helderbergs, the Group thickens to 91 to 107 meters (300 to 350 feet) in the Catskill quadrangle. It continues to thicken farther to the south and southwest.
Alsen and Port Ewen Formations, Helderberg Group
The Alsen occurs in southeastern New York and in the Hudson Valley and is present sporadically as far west as Howe Caverns. The Port Ewen is restricted to southeastern New York and the Hudson Valley. The Alsen is composed of fine-grained, dark-gray limestone with interbedded calcareous and argillaceous shale and is characterized by the presence of bedded and nodular chert. The Port Ewen is a fine-grained siliceous limestone with much interbedded shale and some chert (Rickard 1962). The Alsen in its westernmost, albeit discontinuous, exposures is 2 to 3 meters (6 to 11 feet) thick. South of the Helderbergs the unit is 6 to 9 meters (20–30 feet) thick. Rickard (1962) measured 10.7 meters (35 feet) of Alsen to the south at Austen Glen and concluded from a published description of the rocks that there are 6 meters (20 feet) of Alsen at Kingston. The Port Ewen is 10.7 meters (35 feet) thick at Catskill and on Beacraft Mountain near Hudson. A similar thickness is probably maintained into New Jersey. The Port Ewen at its northernmost exposures is 3 to 5 meters (10 to 15 feet) thick. To the south, it thickens rapidly and reaches an estimated 35 meters (100 feet) at Port Ewen. Near Port Jervis, the thickness of the Port Ewen is approximately 55 meters (180 feet) (Rickard 1962).
Becraft Limestone, Helderberg Group
The Becraft limestone crops out from the New Jersey border north to the Helderbergs in Albany County and west to Schoharie County. In the Helderbergs, the Becraft is described (Rickard 1962) as coarse-grained, crinoidal, dark-gray or pink limestone, with such an abundance of fossils that in places it may be classified as a shellrock or conquinite. It is usually massive, although in some places it has thin-bedded shaley limestone at the base. To the south, the Becraft thickens and can be divided into a lower portion that has many interbeds of green shale and an upper portion of pure limestone with chert nodules. The Becraft is variable in thickness. Between the Canajoharie area and Albany it is 3 to 8 meters (10 to 27 feet) thick. Between Albany and Kingston, the unit is from 14 to 20 meters (45 to 65 feet) in thickness. South of Kingston, the Becraft thins to about 20 feet (Rickard 1962).
New Scotland Formation, Helderberg Group
The New Scotland Formation extends from New Jersey north to the Helderberg Mountains and west to the Schoharie region. In the Helderberg Mountains, the New Scotland is composed of massively bedded calcareous and argillaceous strata which weather gray or brown. Fine-grained, thin-bedded, somewhat siliceous limestone beds are also to be found, especially near the top (Rickard 1962). Westward, the New Scotland is less argillaceous and has more strata of pure limestone, some of which contain chert nodules or beds. South of Canajoharie, the New Scotland is completely replaced by the Kalkberg. South of the Helderbergs, scattered chert nodules are common in this unit at Catskill. The New Scotland becomes more siliceous in the Hudson River Valley and in southeastern New York. Rickard (1962) estimates that the New Scotland is 18 to 21 meters (60 to 70 feet) thick in the Schoharie and Cobleskill valleys. The unit thickens south of Albany. Twenty meters (65 feet) of this unit were measured in the Helderbergs and 22 meters (75 feet) at Catskill. From published descriptions, Rickard (1962) estimated that there are 30 meters (100 feet) of New Scotland at Kingston and 49 meters (160 feet) near Port Jervis.
Kalkberg Formation, Helderberg Group
The Kalkberg cherty limestone extends from Oriskany Falls to the Hudson River Valley, thence south and southwestward into New Jersey. Rickard (1962) describes the Kalkberg as fine-grained, dark-blue, siliceous limestone which is thin to medium bedded with moderately irregular bedding planes. He noted that the most characteristic features are the abundant beds or nodules of black or bluish-black chert and the presence of calcareous and argillaceous shale interbedded with the limestone. In the Hudson Valley the Kalkberg is mostly a medium bedded limestone with some shaley beds in the upper part and with abundant chert in the lower 5 to 7 meters (15 to 25 feet). Locally, as at the Indian Ladder escarpment of the Helderberg Mountains, chert is not at all common and much of the upper Kalkberg weathers shaley (Rickard 1962). Chert is abundant from Canajoharie westward. At the type locality, the Kalkberg is 16 meters (54 feet) thick. Northward, through the Albany region, it is 12 to 15 meters (40 to 50 feet) thick. Its thickness reaches a maximum of 24 meters (80 feet) in the vicinity of Sharon Springs. The unit thins to 2 meters (6 feet) thick at Oriskany Falls, its westernmost exposure.
Coeymans Limestone, Helderberg Group
The Coeymans Limestone is exposed near Syracuse in central New York eastward through Albany, and thence southward to New Jersey. The Coeymans has been divided into three units, the Deansboro, Ravena, and Dayville Members. These three members are not everywhere present. It is present as a single sequence of beds (Ravena Member) only from Cherry Valley eastward. Only the upper portion of the Coeymans (Deansboro Member) extends as far west as the Syracuse region. The lower portion (Dayville Member) extends westward only to the region south of Utica.
From the Helderberg Mountains, north of the village of Ravena, to its westernmost extent at Cherry Valley, the Ravena Member is a pure and very hard, coarse-grained limestone whose resistance to erosion makes it the cap rock of an escarpment. The Ravena has massive individual layers from 25 centimeters (10 inches) to a few meters thick with irregular, wavy bedding planes that give rise to a characteristically rough-weathering surface. Commonly present are coarse-grained lenses or beds almost entirely composed of fossils, both shells and crinoid columns. The fossil brachiopod Gypidula coeymanensis is locally present in abundance.
South of Ravena, the lithology of the Ravena Member is similar except that it is lighter colored (especially when weathered), generally finer grained, and has thinner and less irregular bedding. The Deansboro Member is coarse-grained, hard, and massively but somewhat irregularly bedded. Coarse-grained beds of crinoid columnals are common. Gypidula coeymanensis is present throughout but not in the great abundance typical of the Ravena Member. The remnants of coral reefs (bioherms) are in several very restricted geographical areas. The reef-area rock is composed of extremely coarse-grained fossil accumulations (crinoids, corals, etc.) with bedding obscure or absent. The Dayville Member is a gray, coarse-grained, crinoidal limestone interbedded with dark-blue, fine-grained limestone. The proportion of the latter type of limestone increases from the central part of the outcrop belt westward. The two types are sub-equal in the area south of Utica.
At Cherry Valley the Coeymans Limestone is 30 meters (100 feet) thick. It thins to the east, being 11 meters (36 feet) thick in the Helderbergs south of Albany. The unit becomes thinner to the south of Albany. South of the village of Ravena, the Coeymans strata are generally 3 to 5 meters (10 to 15 feet) thick. It is 3 meters (9 feet) thick on Becraft Mountain and 5 meters (15 feet) thick in Catskill. Southwest of Kingston, the unit thickens slightly to 5 to 6 meters (15 to 20 feet). It may reach nearly 9 meters (30 feet) farther to the southwest (Rickard 1962). The Dayville Member is approximately 12 meters (40 feet) thick throughout, increasing to 15 meters (50 feet) only near Cherry Valley where it becomes the lower part of the Ravena Member. The Deansboro Member is 9 to 10 meters (30 to 35 feet) thick near Cherry Valley where it is transitional into the upper part of the Ravena Member. Its thickness remains relatively constant but does increase to 15 meters (49 feet) near the village of Deansboro. To the west, it thickens to 15 to 18 meters (50 to 60 feet) and has been variably thinned by erosion to 9 to 12 meters (30 to 40 feet) at Oneida Creek, West Stockbridge Hill, and Clockville and to 6 meters (20 feet) at its westernmost exposures at Perryville and Chittenango Falls.
Manlius Formation, Helderberg Group
The Manlius limestone is present across the entire outcrop belt of the Helderberg carbonates. Minor lithological differences within the Manlius have been used to subdivide it into five members. The units are, from oldest to youngest, the Thacher, Olney, Elmwood, Clark Reservation, and Jamesville Members. The Manlius is the finest-grained limestone of the Helderberg Group and is also one of the purest (insoluble residue commonly less than 5–10%). It is dark-colored on a freshly broken surface and weathers a very light gray. Although predominantly fine-grained and thin-bedded, the fine-grained strata of the Manlius are replaced locally, near the top of the formation, by somewhat coarser-grained, poorly bedded fossil accumulations (biostromes) formed of stromatoporoids. These stromatoporoid biostromes are also relatively free of noncarbonate impurities. Where biostromes occur in the Manlius, there are often interlayers of thin-bedded argillaceous "waterlime," which locally are several feet in thickness (Rickard 1962).
Thacher Member, Manlius Formation, Helderberg Group
In New York the Thacher Member constitutes the entire Manlius Formation from the Port Jervis region on the New Jersey border northward to Thacher Park near Albany and westward to Cherry Valley. Only to the west of Cherry Valley do higher members of the Manlius appear, where they are laterally transitional first to the middle and then to the lower strata of the overlying, coarser-grained Coeymans Limestone. At its westernmost extent near Jamesville, the Thacher Member pinches out. The Thatcher, particularly the lower part, contains very fine-grained “ribbon” limestone. Stromatoporoid biostromes often overlie or laterally replace these beds. Where stromatoporoids are not present (such as in the westernmost exposures from Oriskany Falls to Clockville), Rickard (1962) subdivides the Thatcher into a thick-bedded variety, which are 12 to >24 centimeters (5 to >10 inches) thick, and a thinner-bedded variety 2 to 12 centimeters (1 to 5 inches) thick. The thin-bedded variety has argillaceous or calcareous shale partings. Johnson (1958) found that the thin-bedded Thacher in Albany County had nearly 10 percent insoluble residue, whereas the other lithologies had less than 5 percent. The thin- and thick-bedded strata are fine-grained, dark-blue limestone, generally with smooth to slightly irregular bedding planes. At Oriskany Falls, the Thacher is about 11 to 13 meters (35 to 40 feet) thick. It maintains a similar thickness for about 50 kilometers (30 miles) farther west to the area where it pinches out. The thickness of the Thacher varies to the east and south but is generally between 10 and 11 meters (30 to 40 feet) thick between Oriskany Falls and East Kingston. It is 13.7 to 15.2 meters (45 to 50 feet) thick at Howe’s Cave, Schoharie, and Becraft Mountain.
Olney Member, Manlius Formation, Helderberg GroupThe Olney extends from west of Cayuga Lake east to the Sangerfield quadrangle and south of Utica. The lithology of the Olney is similar to that of the Thacher Member of central New York and differs only in being slightly coarser-grained, more massively and irregularly bedded, and in containing stromatoporoid biostromes in stratigraphic positions where the Thacher has none. Rickard (1962) feels that the biostromes in the Olney are discontinuous as those in the Thacher, but notes a persistent one that commonly occurs some 1.5 to 3 meters (5 to 10 feet) from the top of the unit. A biostrome is often also found near the base of this unit. At the most westerly occurrence, the Olney is about 2 to 3 meters (6 to 9 feet) thick. At Skaneateles, the thickness is estimated to be about 10 meters (30 feet). The Olney maintains this thickness eastward to Oriskany Falls.
Elmwood, Clark Reservation, and Jamesville Members, Manlius Formation, Helderberg Group
The uppermost three members of the Manlius crop out in an area from 32 kilometers (20 miles) west of Syracuse, eastward to the Richfield Springs quadrangle, and south of Little Falls.
At Syracuse, the Elmwood consists of upper and lower waterlime beds with a fine-grained limestone in the middle. Rickard (1962) described the waterlimes as drab yellowish-brown, thin-bedded, and mud-cracked. The middle limestone bed often contains stromatoporoids, and Rickard noted that stromatoporoid biostromes are commonly seen where they are also present in the underlying Olney Member. To the west of Syracuse, the middle limestone bed pinches out. To the east of Knoxville, in the Sangerfield quadrangle, the waterlime progressively changes to fine-grained blue and drab limestone (Rickard 1962).
The Clark Reservation is a fine-grained, dark-blue, white-weathering limestone locally characterized by a diagonal fracture system (Rickard 1962). South of Utica, the Clark Reservation becomes thinner, weathers a dark brown, and becomes more argillaceous. The Jamesville Member is composed of fine-grained, dark-blue limestone in thin beds which are locally intercalated with discontinuous stromatoporoid biostromes. East of Syracuse, the Jamesville becomes coarser-grained, brownish-weathering, and slightly irregularly bedded. In quarries near the Syracuse area, the thickness of the upper three members is 12 to 15 meters (40 to 50 feet). The thickness is variable, and this is attributable to the variation of the Jamesville Member, which is 6 meters (20 feet) thick near Syracuse thinning to 2 meters (6 feet) near Utica. The Clark Reservation is 1 to 2 meters (3 to 5 feet) and the Elmwood 3 to 5 meters (10 to 15 feet) thick.
Rondout Formation, Helderberg Group
The Rondout Formation is present from Cayuga Lake to Albany County and southward to the New Jersey border. Although the Rondout has been subdivided into the Glasco and Wilbur limestone, Whiteport and Rosendale dolostone and Fuyk sandstone, in this report the members are not differentiated. Furthermore, the Rondout is not generally acceptable for use as a source of construction aggregate but it is included here because it was quarried near Catskill in the 1990s. It was used for stone crushed to a powder form and mixed with 3/4-inch gravel for use as sub-base for pavers (Item 4). From the Helderberg Mountains westward, the Rondout Formation is a fossil-poor, very fine-grained argillaceous dolostone with some argillaceous limestone and a considerable amount of calcareous shale. Although locally massive, it is generally thin-bedded. To the south of the Helderbergs, the Rondout is thicker-bedded and less argillaceous. The Rondout is about 3 meters (10 feet) thick at Seneca Falls. It is 13 to 18 meters (45 to 60) thick between Marcellus Falls near Syracuse eastward to Oriskany Falls. Six to 7 meters (20 to 25 feet) thick in the Helderbergs, the Rondout thins to 3 meters (10 feet) to the south before thickening again to 10 meters (30 feet) near Catskill. It maintains a thickness of about 10 meters (30 feet) south to Kingston, then thickens to the southwest reaching 15 meters (50 feet) at Rosendale and 16 meters (55 feet) at High Falls. The Rondout continues to increase in thickness to the southwest.
The Cobleskill Formation can be traced from Gallupville in Schoharie County westward along the base of the Helderberg Escarpment to the area of Cayuga Lake. According to Rickard (1962), the Cobleskill Formation contains two major types of rock—fossiliferous limestone and relatively barren dolostone. Limestone predominates between Gallupville and Clockville. Farther west, dolostone dominates the unit except for significant recurrences of limestone near Union Springs and southwest of Seneca Falls. Thickness of the Cobleskill at its type section is variously given as 1½ meters (5 feet) (Darton 1894) to about 2 meters (7 feet) (Prosser 1899), depending upon where the location of the upper contact was taken to be. Rickard (1962) has identified what he believes to be a traceable horizon 9 feet above the basal contact, which marks the boundary between fossiliferous strata in the Cobleskill and a barren, fine-grained dolomitic limestone of the overlying lower Rondout Formation.
The outcrop belt of the Salina group extends eastward from Buffalo to the Helderbergs then southward to Kingston and the Rondout Valley into eastern Pennsylvania (Rickard 1969).
The Salina Group consists of five formations which are, from oldest to youngest, the Vernon, Syracuse, Camillus, Bertie, and the Brayman. The lithology of the Salina Group is largely shale but the Bertie and the Brayman are carbonate units and hence are mentioned here. The Salina Group is approximately 122 meters (400 feet) thick in western New York and thickens considerably to the east to reach a maximum of 305 meters (1,000 feet) near Syracuse and then rapidly thins to less than 30 meters (100 feet) in Schoharie County. In southeastern New York, the Salina increases in thickness from Kingston to eastern Pennsylvania where it exceeds 610 meters (2,000 feet) (Rickard 1969).
The Lockport Group in New York extends 320 kilometers (200 miles) from Niagara Falls to Ilion, where the unit pinches out. At Niagara Falls there are four formations of the Lockport which are, from bottom to top, the Gasport, Goat Island, Eramosa, and Oak Orchard Formations. To the east, in the Bergen quadrangle, the Gasport Formation is replaced by a unit which Zenger (1965) calls the “limestone lentil.” In the Rochester area the Lockport is made up of the Penfield Formation, which is roughly equivalent to the Gasport, Goat Island, and Eramosa. Here, the Penfield is overlain by the Oak Orchard Formation. Between Clyde and Oneida the entire Lockport is composed of the Sconondoa Formation. The Ilion Member makes up the entire Lockport in the Rome, Utica, and Winfield quadrangles (Zenger 1965). The Lockport is generally characterized by brownish-gray color; medium granularity; medium to thick bedding; stylolites; carbonaceous partings; vugs filled with sulphate, sulfide, and halide minerals; and poorly preserved fossils. It is 60 meters (200 feet) thick at Niagara Falls, approximately 55 meters (180 feet) thick in the Rochester area, about 45 meters (150 feet) thick at Clyde, and 23 meters (75 feet) thick at Oneida. In the Rome, Utica, and Winfield quadrangles it is 0 to 21 meters (0 to 70 feet) thick (Zenger 1965).
Oak Orchard Formation, Lockport Group
The Oak Orchard extends from Niagara Falls to the region northwest of Auburn (Zenger 1965). Further east the Oak Orchard becomes the Sconondoa Member. At Niagara, the Oak Orchard is brownish-gray to dark-gray, fine- to medium-grained, generally thick-bedded, saccharoidal dolostone. Sylolites, carbonaceous partings, and vugs are common. Brownish-gray, porous, sandy-textured pockets occur locally. Light-gray chert nodules present in the member at Oak Orchard Creek, along the Erie Barge Canal, and at outcrops in Rochester. Zenger (1965) reported that the Oak Orchard is between 30 and 43 meters (100 and 140 feet) thick in the Niagara–Rochester region.
Eramosa Formation, Lockport Group
Zenger (1965) traced this unit only in the Tonawanda–Lockport area of New York. He described the Eramosa as medium-dark-gray to dark-gray, fine-grained, thin- to medium-bedded, argillaceous, bitumin-bearing dolostone. It is 5 to 6 meters (15 to 20 feet) thick in the Niagara Falls–Tonawanda quadrangles.
Goat Island Dolostone, Lockport Group
The Goat Island Dolostone extends from Niagara Falls east to Sweden, southeast of Brockport. The Goat Island at the reference section is light-olive-gray to brownish-gray, medium-grained, thick-bedded, saccharoidal dolostone. In general, the Goat Island is much less fossiliferous than the underlying Gasport and is more likely to contain chert. Chert nodules are abundant at the top in a thin zone that continues upward into the basal part of the overlying Eramosa. Sporadic nodules are present in the lower part. Stylolites and carbonaceous partings are abundant. Vugs, where they occur, contain gypsum, calcite, and sphalerite (Zenger 1965). Near Niagara Falls the measured thickness is approximately 6 to 7 meters (19 to 25 feet).
Gasport Formation, Lockport Group
The Gasport extends from Niagara Falls through the Albion quadrangle. East of Brockport, the unit loses its identity. Although it is composed of a complex of facies, the Gasport is predominantly olive-gray to brownish-gray, coarse-grained, medium- to thick-bedded, crinoidal dolostone (Zenger 1965). The fossil fragments are coarse-grained and the matrix is much finer-grained and argillaceous. Biostromes and bioherms occur locally. The unit is entirely limestone in some places and entirely dolostone in others with no general trend being apparent.
At the Niagara River, the thickness ranges from 5 to 7 meters (15 to 23 feet). The member reaches a maximum thickness of 10 meters (30 feet) in the Lockport and Gasport areas. Thinning eastward, it is 3½ meters (13 feet) thick at the easternmost exposure.
Penfield Formation, Lockport Group
The Penfield Member occurs from Rochester eastward into the Palmyra quadrangle (Zenger 1965). The basal Penfield is dolomitic sandstone. Above this sandstone, the quartz content decreases and the strata are quartzose dolostones. The dolomitic sandstone is medium- to light-gray, medium-grained, and medium-bedded. Carbonaceous partings, cross stratification, and microstylolites are common. The quartzose dolostones over the sandstone are medium dark-gray to brownish in color. The grain size varies from fine to coarse with the coarser-grained layers containing large fragments of crinoids. Conglomeratic, fossil-fragment zones were observed east of Rochester. The bedding ranges from thin to massive. Coarse, porous, sandy-textured patches and lenses are common in the upper half of the unit. Vugs containing dolomite, sphalerite, gypsum, and other minerals are present throughout. Zenger (1965) reported that the Penfield is between 12 and 18 meters (40 to 60 feet) thick.
Between the Niagara River and the region south of Utica, the rocks of the Lower Silurian Clinton Group crop out in a narrow band approximately 200 miles long and between 5 and 5 miles wide in its broadest extent (Gillette 1947). Near Syracuse, in the central part of its outcrop band, the Clinton Group is subdivided into several formations comprised primarily of shale with subordinate carbonate rock, sandstone, and hematite beds. The Clinton Group is typically not suitable for use as aggregate. However, farther west, the DeCew Formation occurs (Fisher 1960; Brett et al. 1995). The calcareous DeCew formation has been used and is discussed herein. The Clinton Group increases in thickness east from Niagara Falls eastward, reaching its maximum thickness between Rochester and Syracuse. It thins from Syracuse toward its easternmost exposure.
DeCew Formation, Clinton Group
In New York the DeCew extends from Niagara Falls to Rochester. Zenger (1965) described the DeCew at Niagara Falls as medium dark-gray, fine-grained, thin to massively bedded, argillaceous dolostone. Parts of the unit are very convolute, referred to by Grabau (1913) as enterolithic structure. The lower part contains intercalated shale. The DeCew at Rochester is olive- gray to brownish-gray, medium-grained, “enterolithic,” siliceous dolostone. The unit is about 3 meters (8 feet) thick at Niagara Falls and about 5 meters (15 feet) thick at Lockport. It maintains this thickness to Rochester.
The Late Ordovician Trenton Group crops out from the Thousand Island region southeastward through the Black River Valley in Jefferson and Lewis counties, through Oneida and Herkimer counties, and then sporadically crops out around the Adirondacks and east to the vicinity of Glens Falls, Warren County, and north along the Lake Champlain lowlands (Fisher et al. 1970). Trenton Group is subdivided into the Denley, Sugar River, Kings Falls, Rockland, Larrabee, and Amsterdam Formations (from youngest to oldest, respectively) and the Dolgeville Facies of the Denley Formation (Kay 1968; Fisher 1977). These units are primarily limestone with interbedded calcareous shale and marl. The total thickness of the Trenton Group ranges from approximately 122 to 160 meters (400 to 525 feet) in Jefferson County, thins appreciably to the south, and thickens again to the east (Fisher 1977).
Denley Formation, Trenton Group
The Denley Formation crops out as a belt parallel the Black River Valley from the Thousand Islands region southeast to the vicinity of Trenton Falls (Johnsen 1971). Kay (1968) subdivided the Denley into (from oldest to youngest) the Camp, Glendale, Poland, Russia, and Rust Members. The Camp Member is distinctively marly, the Poland Member is calcarenitic, and the Rust Member is a shaley calcarenite with the other members being primarily calcisiltites. The Denley Formation consists of variably shaley calcarenite and calcisiltite and has a distinctly marly lithology (Camp Member) at the base. This formation ranges from approximately 60 meters (200 feet) near Trenton Falls (Kay 1968) to approximately 91 meters (300 feet) near Watertown (Johnsen 1971).
Dolgeville Formation, Trenton Group
The Dolgeville is limited to a belt extending from just north of Norway, Herkimer County, to the vicinity of St. Johnsville, Montgomery County (Kay 1937). Flagler (1966) described the Dolgeville as a black, calcareous to highly calcareous shale, interbedded with dark-gray to dark- brown or black finely crystalline nonfossiliferous argillaceous limestone. Fisher (1977) stated that the Dolgeville Facies is the lateral equivalent of the Denley Formation. The maximum observed thickness of the Dolgeville is 54 meters (177 feet). It pinches out toward the north and the south.
Sugar River Formation, Trenton Group
The Sugar River Formation is the most persistent unit of the Trenton Group in New York, where it forms a belt on the west side of the Black River Valley from the Thousand Islands region southeastward into the Mohawk Valley. Farther east in the upper Hudson Valley and into the southern Lake Champlain region it merges into the Glens Falls Formation (Johnsen 1971). The Sugar River Limestone is a thin-bedded shaley calcarenite and calcisiltite (Kay 1968). It maintains a thickness of approximately 12 to 15 meters (40 to 50 feet) from Watertown to southern Lewis County and thins toward the southeast to a minimum of 2 meters (7 feet) in the Mohawk Valley (Chenoweth 1952; Johnsen 1971). It is reported to be approximately 30 meters (100 feet) thick in the Glens Falls area (Griggs, pers. comm., 2010).
Kings Falls and Rockland Formations, Trenton Group
The Kings Falls Formation is found in Lewis and Jefferson Counties (Kay 1968). The Rockland Formation is present along the belt of Trenton outcrop from the Boonville area in northern Oneida County, where it is quarried, northwest along the Black River Valley through Lewis and Jefferson counties (Johnsen 1971). The Kings Falls Formation is characterized by thick beds of calcarenite and coquinite and frequently contains large ripples (Kay 1968). The Rockland Formation is composed primarily of dark-gray calcilutites, medium-gray fine calcisiltites, and medium-gray fine- to medium-grained calcarenites (Johnsen 1971). The Kings Falls is approximately 30 meters (100 feet) thick at its type section, and the Rockland has a fairly constant thickness of approximately 18 meters (60 feet) throughout New York although it is only approximately 2 meters (6 feet) thick at Canajoharie.
Larabee and Amsterdam Formations, Trenton Group
The Larrabee and Amsterdam Formations are both found along the lower Mohawk Valley with the Larrabee Formation extending northeastward to the southern Lake Champlain region (Kay 1937). Lithologically, the Larrabee consists primarily of thin-bedded limestone which is locally shaley. The Amsterdam is described as a gray-black, rough-fracturing, heavy-ledged limestone. The Larrabee Formation varies in thickness being 15 to 25 feet in the lower Mohawk Valley and up to 35 feet thick in the southern Lake Champlain area. The Amsterdam Formation varies from approximately 10 to 30 feet in thickness.
Black River Group
The middle Upper Ordovician Black River Group crops out as a narrow 192-kilometer (120-mile) long belt from just north of Ingham Mills, Herkimer County, northwestward along the Black River Valley to Watertown and the Thousand Islands region in Jefferson County. In the Black River Valley, the group is less than two kilometers (one mile) in outcrop width and in the vicinity of Watertown, its outcrop is approximately 22 kilometers (14 miles) wide (Young 1943). The Black River is subdivided into three formations which are the Pamelia, Lowville, and Watertown (from oldest to youngest, respectively). The Black River Group increases in thickness from approximately 15 meters (50 feet) at the southern end of the Black River Valley to 45 meters (150 feet) near Lowville in Lewis County, and reaches its maximum thickness of 70 meters (230 feet) in the vicinity of Watertown in Jefferson County (Young 1943). It is absent at Canajoharie but thickens east to the Lake George Lowland.
Watertown, Lowville, and Pamelia Formations, Black River Group
The Watertown Formation only occurs in the vicinity of Watertown in Jefferson County. The Lowville and Pamelia Formations crop out throughout the range of the Black River Group—from Ingham Mills, Herkimer County, northwest to Lake Ontario past Watertown and westward into Ontario (Walker 1973). In the type area, the Watertown Formation appears as two very thick ledges of dark-gray to black, fine-textured, hackly fracturing, semicrystalline limestone (Young 1943). The Lowville Formation is comprised of a complex interbedded sequence of mud-cracked, laminated dolostone; mud-cracked, thin-bedded, medium-grained, bioclastic limestone; oolite; Tetradium (coral) bioclastic limestone; and Loxoplocus (snail) bioclastic limestone (Walker 1973). The Pamelia consists of basal dolomitic sandstone overlain by a variable thickness of pale-gray to buff dolostone.
The Watertown is approximately 4 meters (13 feet) in thickness near its type area. The Lowville varies in thickness from approximately 10 meters (35 feet) at House Creek to 26 meters (87 feet) at Roaring Brook, Lewis County (Walker 1973). The Pamelia Formation ranges from 5 meters (18 feet) at Turin Road to 15 meters (51 feet) at Mill Creek, Lewis County.
The late Lower Ordovician Chazy Group is found in a narrow outcrop belt along the western shore of Lake Champlain in Essex and Clinton counties. It is primarily composed of limestone. The Chazy Group in New York is subdivided into three formations which are (from oldest to youngest) the Day Point, Crown Point, and Valcour (Fisher 1968); of these three, only the Day Point and Crown Point were used for aggregates. Thicknesses of 228 meters (750 feet) to almost 274 meters (900 feet) have been reported for the Chazy. Imperfect exposures and numerous faults make it difficult to obtain accurate measurements of the thickness (Fisher 1968).
Day Point and Crown Point Formations, Chazy Group
The Day Point and Crown Point Formations crop out in a narrow belt along the western shore of Lake Champlain in Clinton and Essex counties. The Day Point Formation consists of a basal quartz-rich unit of cross-bedded sandstone and siltstone (Fisher 1968). The Crown Point is composed of bioclastic wackestone, packstone, and grainstone with variable post-depositional dolomitization (Speyer and Selleck 1986). The Day Point varies in thickness from 80 to 300 feet (Fisher 1968) with rapid areal variations (Oxley and Kay 1959). The entire Chazy group is comprised of the Crown Point Formation at Crown Point, New York, where it is 90 meters (295 feet) thick. The unit thins to 15 meters (50 feet) at Ticonderoga and is thinner at Whitehall, New York (Fisher 1984).
The Upper Cambrian–Middle Ordovician Beekmantown is distributed throughout the St. Lawrence Valley, the Mohawk Valley, the northern Hudson Valley, southern Champlain Valley and Dutchess County (Fisher et al. 1970; Mazzullo 1974; Kröger and Landing 2008, 2010). The Beekmantown is subdivided into six recognizable units in the area in which it crops out. These are, from oldest to youngest, the Galway, Little Falls, Tribes Hill, Rochdale, Fort Cassin, and Providence Island Formations (Kröger and Landing 2010). Lithologically, the Beekmantown Group is composed primarily of marine carbonate and clastic rocks. The lithologies of the economically important calcareous formations of the group are discussed below. In total, the Beekmantown Group is approximately 200 meters (656 feet) thick, although much of the stratigraphy is not economically viable and the units are geographically limited.
In southeastern New York, the name “Wappinger Group” was applied to a discontinuous belt of rocks that extended from Port Jervis in Orange County northeastward to the vicinity of Stissing Mountain in Dutchess County that consists primarily of carbonate rocks (Offield 1967). The name “Wappinger Group” is now recognized as a junior synonym of the Beekmantown Group and Stissing Formation in Dutchess County. In easternmost New York, where metamorphism has masked the characteristics of the subdivisions of the Beekmantown Group, the term Stockbridge limestone or dolostone is used (Fisher 1977). Knopf (1946) reports a total thickness of 1,158 meters (3,800 feet) for these rocks at Stissing Mountain in Dutchess County.
Scotia Member, Fort Cassin Formation, Beekmantown Group
The Scotia Member was once called the “Ogdensburg Formation.” The name has been abandoned (Kröger and Landing 2009a; Landing and Westrop 2006; Landing 2007). The Scotia is present in outcrops in the vicinity of Massena and Ogdensburg in St. Lawrence County (Fisher 1977). It consists of fine-grained, fairly uniform, gray dolostone and sandy dolostone with calcite masses and shale partings common, especially in the lower part of the section (Chadwick 1919). Cushing (1916) described 36 meters (120 feet) of the Ogdensburg Formation in exposures between Morristown and Ogdensburg in St. Lawrence County.
Rochdale Formation, Beekmantown Group
The Rochdale is distributed in discontinuous outcrops in a narrow, northeast-southwest trending belt in the northern Hudson and southern Champlain valleys (Mazzullo 1974; Landing and Westrop 2006). Formerly known as the Fort Ann Formation, the name was abandoned in favor of the senior synonym, Rochdale (Landing and Westrop 2006). The type area is in Rochdale village, Dutchess County. Where it occurs in northern New York it consists of fossiliferous, medium-bedded, finely crystalline, medium-gray, finely laminated limestone with a basal 1- to 2-meter (3- to 7-foot) breccia consisting of dolostone and black chert clasts in a crystalline dolomite matrix. The unit is approximately 28 to 40 meters (90 to 125 feet) in thickness.
Tribes Hill Formation, Beekmantown Group
The Tribes Hill Formation crops out along the Mohawk Valley in Herkimer and Montgomery counties. It is subdivided by Kröger and Landing (2009b) into four sub-units which are the Sprakers, Van Wie, Wolf Hollow, and Canyon Road Members. The Tribes Hill Formation is composed primarily of marine carbonate and clastic rocks. and has an average thickness of approximately 44 meters (145 feet) in the Mohawk Valley. A portion of the Tribes Hill formerly known as the “Great Meadows” Formation, a name now abandoned (Landing et al. 2003; Landing 2007), was quarried where it cropped out in the southern Champlain Valley region. It is comprised of finely laminated or cross-stratified siltstone interbedded with occasional shale and sandstone units, locally cherty, medium-bedded, quartzose, and calcitic dolostone (Fisher 1977; Mazzullo 1974), and finely crystalline, medium-bedded limestone which weathers to a pure-white color. The unit has an average thickness of approximately 85 meters (280 feet) at Smith’s Basin in Washington County.
A unit formerly known as the “Halcyon Lake” Formation in Dutchess County is a synonym of the Tribes Hill Formation (Kröger and Landing 2007). It crops out between Edenville and Warwick, in the vicinity of Florida and is also prominent near Breeze Hill, Orange County. It is a calc-dolomite consisting primarily of lustrous, fine- to medium-grained, mottled-gray dolostone interbedded with very finely crystalline, siliceous, medium-gray dolostone (Offield 1967). According to Offield, the “Halcyon Lake” is so variable lithologically and exposed in such disconnected outcrops that a reliable complete section cannot be pieced together. However, Landing et al. 2010 showed that the same succession of members that make up the Tribes Hill comprise “Halcyon Lake.” The unit here is on the order of 150 to 180 meters (500 to 600 feet) in thickness (Offield 1967), although Knopf (1946) reported a thickness of 107 meters (350 feet) in Dutchess County.
Canyon Road Member, Tribes Hill Formation, Beekmantown Group
The Canyon Road Member has a very spotty distribution. It outcrops between East Canada Creek and Greens Corners in Montgomery County. Lithologically, it is extremely fossiliferous and has a varied lithology consisting of silty, sandy, phosphatic calcarenites, dolomitic calcilutites, pebble conglomerates, calcitic dolomite, steel-gray silty dolomite, and oölitic dolmitic limestone (Fisher 1984). The Canyon Road Member reaches a maximum thickness of 7 meters (22 feet) just west of Tribes Hill in Montgomery County. It thins to the east and west.
Wolf Hollow Member, Tribes Hill Formation, Beekmantown Group
The Wolf Hollow is the most widely exposed member of the Tribes Hill Formation with many exposures present from Little Falls in Herkimer County to near Galway in Saratoga County (Fisher 1954), north to Plattsburg (Landing and Westrop 2006), and south in Dutchess County (Landing 2007). The Wolf Hollow is typically a massive, thick-bedded, white-weathering, blue-black dolomitic calcilutite with dolomitic patches, minor quartz and thrombolites. It maintains a relatively uniform thickness of approximately 6 to 8 meters (20 to 28 feet) throughout its areal extent (Fisher 1954). The “Gailor Dolomite” is now considered a junior synonym of the Tribes Hill (Landing et al. 2010). At the so-called type locality, the “Gailor” is the Wolf Hollow Member.
Sprakers Member, Tribes Hill Formation, Beekmantown Group
Formerly called the Palatine Bridge Member, the Sprakers Member crops out from East Canada Creek in Montgomery County to Hoffmans in Schenectady County (Fisher 1954). It is comprised of fine- to medium-grained, thin-bedded, light blue-gray arenaceous dolomite and silty calcilutite with a large amount of intercalated calcareous shale (Fisher 1954). The Sprakers Member is extremely variable in thickness with a maximum of approximately 15 meters (50 feet) at Flat Creek in Montgomery County, and thins both east and west.
Little Falls Formation, Beekmantown Group
The Little Falls Formation extends primarily from Poland in Herkimer County eastward to the vicinity of Randall in Montgomery County, thinning toward Saratoga Springs in Saratoga County (Zenger 1980). The upper Little Falls was once known as the “Whitehall Formation” in the Champlain Valley but the name has been abandoned (Landing et al. 2003). The Little Falls Formation locally consists of a thick series of dolostone beds which are variable in color and texture. These are usually admixed with rounded quartz grains and frequently penetrated by light-gray or white chert nodules and stringers. Glauconite is occasionally present. Locally, pyrite may be common. Interstitial hematite is prevalent in a reddened zone which is riddled with vugs containing quartz crystals, termed “Herkimer Diamonds,” and anthraxolite (Fisher 1965). At its type section and throughout much of the Mohawk Valley, the Little Falls Formation is approximately 122 meters (400 feet) in thickness.
The Little Falls crops out sporadically between Goshen in Orange County and Stissing Mountain in Dutchess County, where it was formerly known as the “Briarcliff Formation,” now abandoned (Kröger and Landing 2007). It consists of heavy-bedded, light-colored dolostone and calc-dolostone separated by occasional intervening beds of a darker, impure dolostone (Knopf 1956). Chert occurs in scattered nodules and a diagnostic feature of the formation is the occurrence of quartz-calcite druses and black shale partings (Offield 1967). The dolostone is approximately 213 meters (700 feet) in thickness (Knopf 1956).
Galway Formation, Beekmantown Group
Exposures of the late Middle Cambrain Galway Formation occur between Amsterdam in Montgomery County and Saratoga Springs in Saratoga County (Zenger 1980), extend along the Lake Champlain lowlands and appear as upper “Stissing” Formation in Dutchess County (Kröger and Landing 2007). The Galway consists primarily of quartzose dolomite intercalated with dolomitic and calcareous sandstone (Fisher 1956). It is approximately 38 meters (125 feet) thick in the vicinity of Saratoga Springs in Saratoga County.
Noncarbonate Rock Resources
Although carbonate rock is the most commonly used type of rock for construction aggregates, suitable carbonates are not universally available in New York State. Parts of the state are too far from carbonate outcrop belts for the rock to be economically transported to market. In this situation, diverse varieties of noncarbonate rock are used. Depending on the geographic location, sandstone, diabase (trap rock), and various metamorphic rocks can be used. The terminology for the rocks used by the industry is not always consistent with the lithologic definitions of geologists. “Sandstone” can include siltstone, quartzite, conglomerate, and greywacke. “Granite” can encompass coarse-grained igneous rocks, but high-grade gneisses, although metamorphic in origin, are commonly included in with granite. “Trap rock” includes all dense, dark-colored, igneous rocks, regardless of chemical composition or grain size (Tepordei 1985). The general distribution of these rocks is shown on Figure 3. Descriptions of the noncarbonate rock currently used for construction aggregates follow from geologically youngest to oldest.
The Palisades sill is a sub-horizontal, latest Triassic or early Jurassic, diabasic intrusion, locally known as “trap rock.” It is composed of plagioclase, clinopyroxenes, and olivine with accessory biotite, sphene, zircon, and iron-titanium oxides. It is a dense, medium- to fine-grained dark-gray rock with aphanitic contact zones. It is generally mafic in character although small felsic segregations occur. The sill is a composite of multiple stages of intrusion (Puffer et al. 2009). Parts of it are strongly differentiated, the most famous example of which is a 10 meter (~30 feet) thick layer of olivine lying just above the lower contact. Average thickness of the sill is 300 meters (~1,000 feet). The exposed Palisades is about 80 kilometers (48 miles) in length. It occurs along the west wall of the Hudson River Valley from Staten Island north to Haverstraw and thence westward to Pomona (Best 2003). Environmental restrictions have been placed on the extraction of the rock such that no quarrying can occur in the east-facing cliffs, thereby protecting the viewscape from the Hudson River and east side of the river valley. Figure 19 shows a quarry in the Palisades sill.
Diabase (trap rock) quarry in Palisades sill. Lifts are approximately 50 feet.
Wiscoy Formation, Java Group
The Upper Devonian Wiscoy Formation comprises the upper part of the Late Devonian Java Formation in the eastern portion of the outcrop belt of the Java. The Wiscoy interfingers with and replaces the Hanover Member (shale) of the Java Formation in the eastern part of its outcrop belt. The Wiscoy Member varies in thickness between 33 and 58 meters (108 to 190 feet) (Over 1997). It is characterized by medium dark- to dark-gray argillaceous siltstones, silty mudstones, and fine sandstones (deWitt 1960; Haley and Aldrich 2006). At its type locality in Wiscoy Creek, it is a very silty mudrock and siltstone. However, east of there it is near-shore fine-grained sandstone. The outcrop belt of the Java Formation extends from Silver Creek in Chautauqua County eastward to near Addison in Steuben County. However, it is only in the eastern portion of the upper part of the Java Formation that the rock would be useful for construction aggregate.
Walton Formation, West Falls and Sonyea Groups
The Walton Formation is a Late Devonian, nonmarine sublitharenite of relatively uniform composition comprised of sub-angular grains of medium size. Interbedded in this unit are green, gray, and red siltstone and shale. It is often called a graywacke or sub-graywacke depending on the classification system. Both the upper Walton, which is part of the West Falls Group, and the lower Walton, part of the Sonyea Group, are quarried for construction aggregates. It is the sandstone units within these formations that are selectively mined and the siltstone and shale are left in place. This unit is locally worked for aggregates where it contains minimal shaly sones or interbeds. The rock is dominantly quartz (47%) and rock fragments (9%) with interstitial “sericite” (27%), chlorite (6%), muscovite (6%), and plagioclase, K-feldspar, biotite, and opaque phases (<2% each) (Kelly and Albanese 2005). There is evidence of pressure solution and recrystallization at a burial depth estimated at more than 4 kilometers (2½ miles). In the eastern Catskills, the Walton is 365 meters (1,200 feet) thick (Gale 1985). Maximum thickness is estimated at 580 meters (1,900 feet). The upper Walton crops out in eastern Broome, central Delaware, northeast Sullivan, and western Ulster counties. The lower Walton is found in eastern Sullivan and central Ulster counties.
Oneonta Formation, Genesee Group
The Oneonta Formation is composed of red, green, and gray mudstones with subordinate red to gray, very fine- to fine-gained sandstones, either graywacke or sub-graywacke, in beds of up to 6 meters (20 feet) in thickness. Its age is late Middle and early Late Devonian (Bridge and Willis 1994). The mudstones range from fissile and relatively nonbioturbated to blocky and intensely bioturbated with desiccation cracks throughout and represent flood-basin deposits. The sandstone sets are sharp-based, sheets and lenses, cross-bedded or planar-bedded flood deposits. The major sandstone bodies are interpreted as fluvial channel deposits. It is approximately 275 meters (900 feet) thick (Gale 1985). This formation crops out in central Chenango, northern Delaware, central Greene, and southwestern Schoharie counties. It is worked locally for aggregates where it contains minimal shaly zones.
Mount Marion Formation, Marcellus Subgroup, Hamilton Group
The Mount Marion is a Middle Devonian marine unit composed of fine-grained sandstone, siltstone, and shale in eastern New York. The upper portion of the formation, the top of the Otsego Member, is reworked, near shore sandstone which can be quarried for construction aggregates. Lithologically, this rock is shaley sandstone, sandstone, and quartz and minor chert pebble conglomerate. Total thickness of the Mount Marion is about 213 meters (700 feet). Thickness of the sandstone-dominated rock is about 100 meters (328 feet). The Mount Marion forms a belt of rock that crops out from Cherry Valley, Otsego County eastward through the Helderbergs, and south to Kingston in Ulster County. This unit is used for aggregates at Coxackie in Greene County.
Bellvale Formation, Hamilton Group
The Bellvale Formation is dominantly dull-gray fine- to coarse-grained flaggy sandstone (60%) with interbedded siltstone and shale (40%), the latter being more prevalent at the bottom of the unit. The rock is texturally immature to sub-mature but is a well-indurated sandstone. It is composed of angular quartz, chert, and phyllitic rock fragments in a microgranular quartz matrix with variable sericite and chlorite. The rock is classified as a sub-graywacke or lithic greywacke and ranges to lithic arenite (Jaffe and Jaffe 1973; Kriby 1981). The quartz grains are sutured and indicate partial recrystallization (Offield 1967). Quartz veins and fracture fillings are common. Conglomeratic beds occur throughout, and become more common at the top of the unit. The unit is Middle Devonian in age, and referred to the Hamilton Group. The Bellvale Formation crops out in two belts in a narrow northeast-trending overturned syncline in Orange County. The unit is estimated to be 396 to 610 meters (1,300 to 2,000 feet) in thickness. The outcrop belt extends from the New York–New Jersey border and pinches out about 10 to 11 kilometers (6 or 7 miles) southwest of Castleton-on-Hudson. This unit is worked for aggregates in Woodbury, Orange County.
Grimsby Formation, Medina Group
The Medina Group (Lower Silurian) is a deltaic to nearshore, shallow marine unit. It is from 24 meters (80 feet) to 35 meters (115 feet) thick and consists of white, green, and red sandstone, siltstone, and shale (Martini 1971). The formation as a whole is grossly lens-shaped. It crops out along the south shore of Lake Ontario. It includes the Whirlpool Sandstone, Power Glen Shale, Devils Hole Sandstone, Grimsby Formation, Thorold Sandstone, Cambria Shale, and Kodak Sandstone in an upward succession. The Grimsby sandstone is quarried for aggregates in two layers totaling about 14 meters (45 feet) in thickness. The Grimsby is a hematitic quartzose sandstone, red in color with gray mottling and is fine- to medium-grained. It contains red-gray mottled greywacke, siltstone, and shale interlayers (Lumsden and Pelletier 1969). It tends to become more silty or shaley in the lower portion of the unit and this is intensely burrowed and fossiliferous. Shale pebble conglomerates represent reworked material from older rocks that have been incorporated into the Grimsby. The Medina can be traced from Hamilton, Ontario to Fulton, New York.
The Potsdam Formation is middle-upper Middle Cambrian sandstone that is divided into two members (Landing et al. 2009). The Keeseville Member, which is currently quarried for aggregates, is a white to buff, tan-weathering homogeneous quartz arenite. Feldspar is 10 percent or less of the rock, which is silica-calcite-cemented. Fisher (1968) ascribes the rock to a low-energy, intertidal or shallow sub-tidal environment of bays and lagoons protected by barrier islands. The Ausable Member lies under the Keeseville and is tan to pink arkosic sandstone with quartzose shale interbeds and quartz pebble conglomerate lenses (Fisher 1968, Landing et al. 2009). The feldspar component of the rock is locally up to 50 percent. Zircon, magnetite, hematite, biotite, pyroxene, and hornblende are accessory minerals. The Potsdam discontinuously rims the Adirondack Mountains except in the Black River Valley. It is thickest in the area from Fort Ann, 40 meters (130 feet), to Ausable Chasm, 139 meters (455 feet), and thickens to 750 meters (2,460 feet) north of Plattsburgh. The total thickness is difficult to determine due to lack of continuous exposure. A reasonable assumption for the northern Champlain Valley is about 750 meters (2,460 feet). The Ausable was probably deposited in high-energy fluvial and tidal channel bank environments.
The Rensselaer is largely limited to one thrust slice in the Taconic overthrust. It is of Early Cambrian age. The unit is a primarily turbidite, a feldspathic greywacke consisting of pebble conglomerate to medium sand. The Rensselaer is made of quartz with muscovite and rock fragments (argillite) interbedded with (Mettawee) red and green slate and argillite. It is hard, quartz-rich greywacke with a matrix of silt or fine sand (quartz dominant), feldspar (plagioclase and microcline), chlorite, and other micas. It is dark-green or gray on fresh surface and weathers brownish-gray. It displays massive bedding 0.6 to 3 meters (2 to 10 feet) and is coarser-grained on the west half of the Rensselaer Plateau. On the west face of the plateau, two sections are separately recorded at 274 meters (900 feet). Potter (1973) reports that it may be much thicker in the central part of the plateau. Total thickness is probably 365 to 396 meters (1,200 to 1,300 feet). The Rensselaer is a rather restricted geologic unit in New York. It primarily occurs within central and eastern Rensselaer County, where it is an important source of aggregates, with minor outliers. Major quarries are located in Cropseyville, Rensselaer County. It occurs from Boydonton to East Nassau in a north–south direction and east–west from Postenkill to Berlin. Its outcrop area is roughly 35 x 15 square kilometers (22 x 9 square miles).
The Everett Formation is a gray or greenish fine- to medium-grained schist or phyllite. It is composed of quartz, plagioclase (albite or oligoclase) muscovite, garnet, with minor staurolite, chloritoid, and chlorite. It is probably of Early Cambrian age. Where it is quarried for aggregates, it is of slightly higher metamorphic grade and has a gneissic texture with bands of biotite and hornblende. The Everett schist is at least 465 meters (1,500 feet) thick. The unit crops out in the eastern Taconic Mountains in several thrust fault-bounded slices that trend northeasterly though eastern Dutchess County and on the New York–Massachusetts border in Columbia County. Metamorphic grade in the Taconic Mountains increases eastward and southward so it is likely that only in southeastern New York will the Everett be of suitable quality for use as an aggregate. In the central and northern Taconics, the Everett Formation is a fine-grained, well-foliated phyllite, unsuited for construction aggregate.
Throughout the Adirondacks and to a lesser extent in the Hudson Highlands, high-grade metamorphic rocks are extracted for construction aggregates. The rocks are meta-igneous and meta-sedimentary in origin (Figure 19), generally having been subjected to upper amphibolite or granulite grade metamorphism during the Grenville orogenic cycle. In some cases these are named units, but more commonly they are not, as the regional stratigraphy of these regions is not established with certainty. These rocks have been subjected to strong deformation, and were thickened by intense folding and thinned or repeated by large scale shearing. Overall thicknesses of the units are estimations. Commonly, the thickness of a given unit will be on the order of hundreds to thousands of feet. Hence, the site geology of a quarry is more important than the overall thickness of the rocks to be mined. The rock units are large and regionally homogeneous but modal variations of the mineral phases occur commonly.
Most commonly quarried are rocks that are broadly classified as “granitic gneiss,” although the mineralogical and bulk chemical composition varies from granite sensu stricto to quartz syenite, syenite, granodiorite, and diorite. Interlayered with these rocks is amphibolite composed of plagioclase and amphibole minerals. Also interlayered are pure or feldspathic quartzite, calc-silicate gneiss, and marble. All of these rocks are successfully quarried in areas underlain by Precambrian rocks in New York. Specific examples of rock mined for aggregates are described below.
In Warren County, folded granite gneiss and amphibolite are quarried at a mine where approximately 100 meters (330 feet) of quarry rock are exposed. The granite gneiss is composed of plagioclase, quartz, potassium feldspar, hornblende, and garnet. This unit is interlayered with amphibolite, which is primarily plagioclase and hornblende. In Essex County, several types of rock are used for construction aggregates. Some are meta-sedimentary in origin and include quartz-plagioclase (± K feldspar) gneiss, coarse-grained diopsidic marble, and amphibolite. These units, taken together, make up over 128 meters (420 feet) of mined rock. Also in Essex County, meta-igneous rocks in the form of meta-anorthosite and interlayered diorite gneiss are used for aggregates. The meta-anorthosite is dominantly plagioclase feldspar, with 10 to 20 percent iron-magnesium bearing silicates such as amphiboles, biotite, and garnet with minor iron oxide minerals. The diorite gneiss is composed of sodic plagioclase feldspar and mafic minerals.
The Green Lake Formation is quarried in the southern and central Adirondacks. McLelland (1972) describes this unit as being between 60 meters (200 feet) and 600 meters (2,000 feet) thick. This unit is dominantly a light-colored garnet, quartz, plagioclase, K feldspar, sillimanite gneiss interlayered with minor amphibolitic, calc-silicate, and biotite-rich gneisses. Locally, there are layers of quartzite of variable purity. In Washington County, the Hague Gneiss, oldest unit of the Springhill Pond Formation in the Lake George Group (Fisher 1985) is quarried. This is a banded quartz, plagioclase, sillimanite, biotite, hornblende, garnet, potassium feldspar, gneiss, which contains bodies of amphibolite. In northern Oneida County, quartz granofels, quartz syenite gneiss, and biotite gneiss are used for aggregates. The quartz granofels is a phaneritic, nonporphyroblastic, nonfoliated unit composed of plagioclase, quartz, and biotite. The quartz syenite is a feldspar, quartz, minor biotite, and chorite gneiss, and the biotite gneiss is plagioclase, quartz, and biotite (McLelland 1972). In Fulton County, the Peck Lake Formation is quarried. This is described by McLelland (1972) as a garnet, biotite, quartz, plagioclase (oligoclase) gneiss with amphibolite and quartzite layers. Overall, this unit is estimated to be 1,525 meters (5,000 feet) thick. While leucocratic variants of the Peck Lake exist, it is not possible to further sub-divide this formation. A 150-meter- (500 feet) thick unit of granodiorite and diorite gneiss is also quarried. In Franklin County, the so-called St. Regis Granite Formation is used for construction aggregates. This is comprised of granitic gneiss mixed with amphibolite several hundred feet thick. The gneiss is made of K-feldspar, quartz, and hornblende.
In the metamorphic rock of the Hudson Highlands of Dutchess County, undifferentiated granite gneiss and hornblende granite gneiss of the Grenville orogen are quarried. The rocks are composed of quartz, K-feldspar, and hornblende with minor pyroxene, garnet, epidote, and chlorite. Minor dolomitic marble is interlayered with these rocks.