The basal phosphatic-quartz pebble bed of the Williamson Shale (Clinton Group) is here named the Second Creek Bed for exposures along Second Creek, north of Alton, Wayne Co., NY. The lower part of the bed is stained red and contains abundant pyrite, phosphatic pebbles, and quartz granules. Upper part is characterized by phosphatic pebbles, quartz granules, and abundant brachiopods. Bed is widespread and ranges in thickness to 20 cm. The Williamson is exactly equivalent to the Willowvale Shale as both are bounded by the same biostratigraphically-dated discontinuity surfaces. The Second Creek Bed is laterally equivalent to the Westmoreland Iron Ore at the base of the Willowvale. Age is Early Silurian (late Llandoverian).

Source: GNU records (USGS DDS-6; Reston GNULEX).

The Williamson Shale of the Clinton Group in western NY consists of greenish-gray to black, fissile to platy, graptolite-bearing shale with a thin quartz and phosphate pebble bed at its base (the Second Creek Phosphate Bed). Thickness ranges from a featheredge in Niagara Co. to 78.5 ft at Lakeport, Oneida Co. Unit is well exposed in Browncroft Creek and at the Genesee River Gorge in east Rochester, NY. Unconformably overlies the Merritton Limestone, Reynales Limestone, or Neahga Shale, and unconformably underlies the Rockway Dolomite. Eastward, the Williamson thickens and grades laterally into the Willowvale Shale near Utica, NY; westward, unit thins and pinches out between Lockport and the Niagara River Gorge. The Williamson is of Early Silurian (latest Llandoverian) age. [Report uses Early and Late Silurian time scale of Harland and others (1982).]

Source: GNU records (USGS DDS-6; Reston GNULEX).