Publications

Abundant and diverse Lower Cambrian faunas occur in a characteristic siliciclastic-dominated Avalon Platform sequence in eastern Massachusetts. The lowest Cambrian unit, the North Attleboro Formation (new), nonconformably overlies upper Precambrian intrusives and is the local representative of a quartzite-dominated facies that is regionally extensive in the middle part of the Avalonian sub-trilobitic Lower Cambrian. The North Attleboro Formation is unconformably overlain by the shale-dominated Weymouth Formation (emended). Nearshore (Hoppin Hill area) and offshore (Boston Basin) environments are represented in the Weymouth Formation. The "Hoppin Formation" and "Pirate Cave Formation" are local designations for the Weymouth Formation, and use of these designations should be discontinued. Three faunas are known from the Weymouth Formation: the sub-trilobitic upper Aldanella attleborensis assemblage and the Camenella baltica assemblage (=Coleoloides typicalis assemblage of other authors) and the trilobite-bearing middle Callavia Zone. Most of the small shelly fossils from the Weymouth Formation are geographically widespread and, consequently, represent species that exhibit remarkable evolutionary stasis and extremely long, stage-magnitude stratigraphic ranges. Finely resolved interregional correlations of the uppermost Precambrian and Lower Cambrian based on small shelly fossils are not possible because of these features. Thirty-six species known from calcareous tubes, phosphatic sclerites, conodont-like elements, mollusk and brachiopod shells, and trace fossils are described. Plinthokonion arethion n. gen. and sp. is known from tubes composed of size-selected mica flakes with a phosphatic cement. Trypanites? ichnosp. represents the oldest reported macroborings. The type species of Anabarites, A. trisulcatus, is regarded as a morphologic variant and junior synonym of Tiksitheca korobovi.