• Member description taken from 2007 Long. Tempestite frequency curves: a key to Late Ordovician and Early Silurian subsidence, sea-level change, and orbital forcing in the Anticosti foreland basin, Quebec, Canada. Can. J. Earth Sci. Vol. 44, 413-431. "The Merrimack Formation (Copper and Long 1989) consists of up to 25 m of dark grey, recessive weathering calcareous mudstones, with minor micrites and calcarenites. At the east end of the island the formation contains a few prominent ledges of medium to fine sand-grade calcarenite, characterized by hummocky or swaley cross-stratification. Some of these laterally discontinuous beds have scoured bases. Abrupt lateral termination of some beds may indicate early lithification and partial removal by later storms (Fig. 4A). Associated resistant ledges of apparently massive micrite may also be of storm origin. They are characteristically 10 to 12 cm thick and have a sharp flat to wavy base, and a pitted top, with 5% to 10% Planolites burrows."