The Fruitiness of August. The Silurian Reef mounds and coral biostromes

Reef mounds (bioherms) provided the Silurian seafloor with an organically constructed microtopography featuring zonations of segregated brachiopods, gastropods (class of mollusk containing present-day snails and slugs), crinoids (class of echinoderm containing present-day sea lilies and feather stars), and trilobites. The Thornton Reef Complex outside Chicago is an example of a well-zoned Wenlock complex more than 1 km (0.6 mile) in diameter. Others are well known from the Silurian of Manitoulin Island (Ontario, Can.), northern Greenland, Shropshire (Eng.), Gotland (Swed.), Estonia, the central and southern Urals of Russia, and Siberia. The most spectacular complex is a barrier reef 350 km (215 miles) long of late Llandovery–early Wenlock age in northern Greenland.