Lower, middle, and upper Cambrian faunas in the Taconic sequence of eastern New York; stratigraphic and biostratigraphic significance

Three Lower, two Middle, and two Upper Cambrian trilobite faunas from the Taconic sequence in the region of Columbia County, New York, contain diagnostic genera and species in unquestionable stratigraphic order, allowing precise correlation with Cambrian strata of other regions of North America and Europe. The trilobites occur in lenticular limestones which are interstratified with a greater thickness of grey, green, or black unfossiliferous shales. These findings indicate no unconformity exists between Lower Cambrian and Lower Ordovician strata of the Taconic sequence in the southern portion of the Taconic allochthon, and that an essentially complete sedimentary sequence probably extends from the Cambrian system upward into the Lower Ordovician.