The Willowvale Shale is exactly equivalent to the Williamson Shale because both are bounded by the same biostratigraphically-dated discontinuity surfaces. Earlier correlations of the upper Willowvale with the Irondequoit are in error. The Williamson-Willowvale sequence records a major marine transgression with at least one major regressive subcycle. New litho- and biostratigraphic data support Gillette's (1947) original contention that the underlying Westmoreland Hematite is genetically related to the Willowvale. Age of both units is Early Silurian (late Llandoverian).
Source: GNU records (USGS DDS-6; Reston GNULEX).
For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.
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