This publication presents a description of 137 wells in New York State and adjacent parts of Pennsylvania. Correlations with surface exposures are established. Maps and cross sections display the thickness, structure, and stratigraphic relationships of the carbonates described. A paleogeologic map of New York State at the end of the Early Ordovician is presented. Two distinct series of rocks which comprise the Cambrian and Ordovician carbonates of New York are described and studied in detail. The monograph includes an extensive bibliography, several schematic figures and diagrams, and two appendices which give data relevant to the identification of control wells and subsurface data from control wells. (Author/EB)