Petrographic analysis of selected samples from the Sauk interval of the Branagan#1 Well reveals that this interval consists of heterogeneous series quartz arenites, feldspar, and carbonate minerals in forms of dolostone and limestone. The lithologies of the Sauk Sequence consist of a basal sandstone sheet (Potsdam Formation) overlain by a carbonate sequence (Theresa Formation). This sequence was divided into microlithofacies based on the lithologic heterogeneities, and sedimentary microstructures. These microlithofacies were deposited within a peritidal environment of a shallow marine setting.

Using a cathodoluminescent microscope, the Sauk Sequence of the Branagan#1 Well records a timing sequence of diagenesis as follows: 1)syndepositional stage (deposition of the detrital quartz); 2) early burial stage (quartz overgrowth and early dolomitization); 3) late burial stage (carbonate cementation and dedolomitization).

Lithologic heterogeneity in the Branagan#1 Well has affected the reservoir quality of the Sauk Sequence in eastern New York State.