NEW STRATIGRAPHIC LEXICON FOR MICHIGAN

A new Stratigraphic Lexicon for Michigan has recently been produced by the Michigan Basin Geological Society and the State of Michigan Geological and Land Management Division (GLM). The Lexicon contains names and descriptions used for Michigan stratigraphic units. Formal and informal units are included. There are two types of stratigraphic entries in the Lexicon. Those that provide the most information are the formal stratigraphic units, which are also included in an accompanying new stratigraphic column chart. The format for formal stratigraphic unit entries includes the unit name, geologic age, related terms or synonyms, lithology and thickness, type locality with original reference citation, related additional literature citations, and remarks. The other type of entry is for informal or invalid stratigraphic terms or valid stratigraphic terms from other regions that have been incorrectly applied to Michigan strata. This volume is designed to update the Index of Michigan Geology, 1956, Martin and Straight, Michigan Geological Survey. No comprehensive review of Michigan stratigraphy has occurred in the intervening 45 years. The Lexicon contains a section describing current, unresolved, stratigraphic problems in units from Cambrian through Jurassic encompassing the majority of the sedimentary section in Michigan. The Lexicon also contains an extensive bibliography and chronologic index of all formation names. Accompanying the Lexicon is a 17 by 22-inch color stratigraphic chart with graphic lithologies and outcrop and subsurface correlations. The chart is also available online from the State of Michigan Geological and Land Management Division at: http://www.deq.state.mi.us/documents/deq-gsd-info-geology-Stratigraphic.pdf