Historical:Metz Member
Lithostratigraphy: Ottawa Limestone Megagroup >>Ancell Group >>Joachim Dolomite >>Metz Member
Chronostratigraphy: Paleozoic Erathem >>Ordovician System >>Champlainian Series >>Blackriveran Stage
Allostratigraphy: Tippecanoe Sequence
Authors
H. B. Willman and T. C. Buschbach
Name Origin
The Metz Member of the Joachim Dolomite (Templeton and Willman, 1963, p. 62), which overlies the Matson Member, is named for Metz Lake, 5 miles north of the type section.
Type Section
The type section of the Metz Member is in a quarry in the east bluffs of the Mississippi River, just north of West Point Landing, Calhoun County (SE NE SE 19, 7N-2W), where the member is 9.5 feet thick.
Extent and Thickness
The Metz Member is present throughout the area of the Joachim Dolomite and commonly is about 15 feet thick, ranging from 7-20 feet.
Description
The Metz consists of light gray, silty, thin- to medium-bedded dolomite but has a few beds of pure, darker dolomite. It contains algal domes, mud-cracked surfaces, and scour surfaces. It differs from the underlying relatively pure Matson Member, but many of the beds have a lithology similar to that of the Defiance and Augusta Members. The dominance of dolomite differentiates it from the relatively pure, lithographic limestone of the Platteville Group, which overlies it unconformably.
References
TEMPLETON, J. S., and H. B. WILLMAN, 1963, Champlainian Series (Middle Ordovician) in Illinois: Illinois State Geological Survey Bulletin 89, 260 p.
ISGS Codes
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