Lower, Middle, and Upper Cambrian Faunas in the Taconic Sequence of Eastern New York: Stratigraphic and Biostratigraphic Significance

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Abstract
An intensive search for fossils in Taconic sequence strata in the region of Columbia County, New York, produced three Lower Cambrian, two Middle Cambrian, and two Upper Cambrian trilobite faunas, of which only the oldest Early Cambrian fauna was previously known from the area. All these faunas contain diagnostic genera and species, allowing precise correlation with Cambrian strata of other regions of North America and Europe. The trilobites occur in limestone units which are generally lenticular and interstratified with a much greater thickness of grey, green, or black unfossiliferous shales. These findings indicate that there is no unconformity between the Lower Cambrian and the Lower Ordovician strata of the Taconic sequence in the southern portion of the Taconic allochthon. It is likely, instead, that an essentially complete sedimentary sequence extends from the Cambrian system upward into the Lower Ordovician. Several sections were measured, and are described in detail, with lists of the fossils observed at various stratigraphic positions. For the first time in the study of the Cambrian of the Taconic sequence, several diagnostic faunas in unquestionable stratigraphic order have been collected from a single section. Aspects of the stratigraphy of the Columbia County region are compared with those determined by recent investigations of the northern portion of the Taconic allochthon, and sedimentary aspects are briefly described.

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