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Meander C: The Evidence
By far the most complex, and on initial inspection the least likely, meander area being considered as the site of the 1730 canal project is Area C. Area C is also the least easily seen of the three and is virtually invisible except on aerial photographs. It lies to the east of Area B, about midway between B and the mouth of Sauquoit Creek.
Whereas Area A was a cut-off meander lying intact alongside the original river channel, Area C is in an area of construction and channelization that obscures not only its position but that of the old river bed as well. The rechannelization evident in this area all derived from the construction of the Barge Canal in 1918. Because the large northward loop of the river discussed above on the 1784 map had to be cut through by the canal trough, a by-pass channel was constructed to link the severed ends of the river and continue the flow of water downstream. This connecting channel can be clearly seen running parallel to the canal just west of Sauquoit Creek (below). The path of this artificial channel also cut through the lower section of a cut-off meander of the river, which we are calling Area C.
It is interesting to note that although this meander loop appears on none of the early historic maps we have been examining, its position is quite evident on some of them due to an awkward jog in the river (at arrows) at the point where the meander cut-off occurred. This jog can be seen clearly on both the 1811 and 1803 (below) surveys of Benjamin Wright, although no hint of the old meander is revealed.
The only maps that contain evidence of this meander loop are relatively recent ones; the 1908 canal map31 (below left) which represents the feature as an egg shaped swamp or marsh, and the 1898 USGS map32 (below right) which shows the meander partially water-filled and still connected to the main channel at the downstream end.
Area C is distinguished from either A or B by the presence of a number of fairly obvious meander scars along the west side of the main river channel, suggesting previous positions of the river while the meander loop was still open. Also present on the west side of the feature is a very well defined dry bed immediately adjacent to the water-filled trough. This was the terminal river channel prior to construction of the Barge Canal. Between this old section of the main channel and the western arm of the meander loop is an elevated ridge of land that is roughly the same height as the land in the interior of the loop (ox-bow). This suggests lateral movement of the west branch of the main channel eastward, with placement in the position of the dry channel for a considerable length of time prior to its terminal location.
Near the point northward where the cut-off crosses the bed of the west arm of the ox-bow, this intervening ridge becomes less defined on its eastern side, while remaining well defined on its west/northwest side. This suggests that the main river channel at the cut-off continued to migrate northwestward at the same time the more westerly part of the channel was migrating eastward. This accounts for the S-shape of the channel at this location that is so distinctive on the 1803/1811 mapping. The west arm of the ox-bow has been partially filled reducing its watercourse to a narrow ditch-like feature which may have been dug after 1918 to drain off excess water from the old river bed. These modifications obscure the precise location of the original gap at the neck. The east arm of the ox-bow is set against a significantly higher mass of land to the east than that seen within any part of the meander area. Two distinct troughs exist at the northern termination of this arm of the meander. One, the more easterly, is separate and slightly more elevated than the more westerly, suggesting it is of greater age, as the lower and more defined westerly trough clearly was carrying the load of the river prior to final cut-off. This may suggest that the east arm of the meander loop was migrating westward at the neck prior to cut-off, thus producing a contracting, not expanding, neck. The evidence observed in the field suggests that prior to cut-off these arms of the meander loop at the neck were little more than a few yards apart, creating not only a very narrow bit of land, but also imposing two rather severe cut-back turns on any boatmen who tried to navigate through.
The ox-bow, except in the immediate area of the neck, has the appearance of stability found in Area A and the unconstructed portions of Area B. However, there is evidence of significant hydrodynamics ongoing at the neck/cut-off area. First of all, if we project the alignments of the two arms of the ox-bow northward, we see (right) that the terminal main river channel at the cut-off is some distance north of the point that these arms would have met, i.e., the river here has continued to migrate away from the original cut-off. But, the fact that the land separating the main channel from the western arm of the meander loop is elevated and pronounced, thus preventing over-bank flood deposits within the west arm of that loop, coupled with the fact that both arms of the loop are heavily filled with silt, suggests that the meander was still receiving a depositional load from the main river channel after the cut-off. We might explain this filling phenomenon merely in terms of backwash from the migration of the main channel northward after the cut-off, starting from a point on the west arm of the loop where it is silted in. But if that were the case, we would not expect to see remnants of the original meander loop channels at both the east and west ends. We would rather have a true ox-bow, cut off and completely isolated by floodplain deposit, as we do elsewhere on the river where this has occurred prehistorically. We can only assume that the loop and the main channel remained connected after the cut-off, just as shown on the British maps, with the slowed waterborne sediments being dropped out as they flowed into the upper ends of the open arms of the loop, but the watered channels of the loop remaining well defined by virtue of their continued connection to the active river. This would have promoted some cutting during peak flow periods, followed by less pronounced filling during the slack water phase.
Note that of the three meander areas studied, Area C shows the greatest degree of movement, i.e., channel migration. This is particularly observable to the west of the water filled river bed, where a well defined dry channel can be seen, much deeper than the scars of any previous position of the river here to the west. Is it possible that the destabilizing effects of an artificial cut, which had to significantly change the physical dynamics of the river in this location, produced the relatively rapid adjustment of the river just upstream from the cut-off, with the river manufacturing a classic S-curve in the channel to absorb some of this added energy? Certainly none of the other meanders exhibits this degree of movement.
Any straight-line water channel will, over time, begin to meander. In uniform soils, and all things being otherwise equal, the channel will begin (left) to take on an S-shaped course. If the river is also required to absorb a greater force of water than normal, this S-curve develops more rapidly. In essence, the river is trying to lengthen its course in order to absorb a greater volume of water at a uniform velocity. Certainly a cut at the neck at C (above, right), which would have shortened the normal length of the river here by over 500 yards, would have focused that added pressure at the cut-off. The accentuated S-curve at the cut-off, and the deep and dry river channel immediately to the west and apparently rapidly abandoned, may be evidence of this phenomenon.Although small in size, and seemingly a poor cause for so great an excavation effort as a canal, this neck probably fit exactly the characteristics considered prerequisite for such a navigation improvement in the early eighteenth century. This point can perhaps best be proven by reference to the only other"Neck" identified in this navigational system in the eighteenth century, namely "the Neck in the Wood Creek." Home
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