Stromatoporpoids more common on leeward side

Ref. 1843:
The Early Silurian is a critical time for understanding the evolution of corals and their role as reef-builders. By the middle Early Silurian, corals and stromatoporoids were the primary reef-building organisms. The Brassfield Formation (Llandoverian) in southwestern Ohio consists principally of nearshore bioclastic grainstones and packstones with occasional boundstones and minor shale intervals. Numerous coral-stromatoporoid patch reefs reported from the Brassfield are among the oldest known in the United States. Unlike other Silurian reefs in the U.S., Brassfield reefs are undolomitized and well-preserved. These conditions allow observation of fine-scale morphological details and permit a detailed taxonomic and paleoecologic comparison with other Silurian reef communities.  Fossil material (in situ and from float) was collected from a Brassfield patch reef exposed in the Reed North Quarry, Fairborn, Greene County, Ohio. Approximately 350 fossil specimens were identified during preliminary mapping of at least 72 square meters of the patch reef. In order of abundance, the reef-building organisms include favositids (176 colonies), stromatoporoids (109 specimens), colonial rugosans (37 specimens), halysitids (16 colonies), and solitary rugosans (9 specimens). A few specimens have encrusting crinoid or bryozoan holdfasts. Initial observations indicate that this Brassfield patch reef is consistent with the model of a typical Early Silurian reef.