TENTACULITOIDS FROM THE UPPER SODUS SHALE, SILURIAN, WESTERN NEW YORK

The Sodus Shale, a portion of the Lower Clinton Group, is a greenish-gray, fossiliferous silty shale that overlies the Reynales Limestone and is unconformably overlain by the Williamson Shale, a unit that is notable for current aligned graptolites. At Palmer’s Glen in Rochester, New York, the upper Sodus Shale consists of three distinct shale units separated by light gray, brachiopod grainstones. Tentaculitoids, preserved as external molds as well as calcite or pyrite internal molds, are relatively common in thin carbonate laminae as well as within the shale. The fauna is dominated by Tentaculites minutus Hall, 1843, which is characterized by a ~ 6 mm long conch with evenly spaced angular primary rings; the interspaces contain evenly-spaced annulations parallel to the primary rings. Oriented samples containing T. minutus were collected from limestone laminae in the lower and middle shale beds. The azimuth of the long axis of complete, unbroken specimens (n=51) were recorded and plotted on rose diagrams. Around 45% (23/n) of the tentaculitids had a NE-SW orientation and 10% (5/n) were NW-SE, perpendicular to the dominant orientation, suggesting a NE or SW paleocurrent. Previous work in the overlying Williamson Shale interpreted a to-the-south downslope paleocurrent based on N to NE oriented graptolites.