Mauch Chunk Formation
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The Mississippian Mauch Chunk Formation (Mmc) is a mapped bedrock unit in Pennsylvania, Maryland, and West Virginia. It is named for the borough of the Mauch Chunk now currently known as Jim Thorpe, Pennsylvania.
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[edit] Description
The Mauch Chunk is defined as a grayish-red shale, siltstone, sandstone, and conglomerate. The Loyalhanna Member is a local limestone and sandy limestone at its base, as well as the Greenbrier and Wymps Gap Members. Along the Allegheny Front, the Loyalhanna is a greenish-gray, calcreous, cross bedded sandstone.[1]
[edit] Depositional Environment
The early Mauch Chunk beds were deposited on a large basin receiving most of its sediments from distant highlands. Sea levels fluctuated and allowed some limestone deposition to occur early as well. Since the dominate color of the Mauch Chunk is red, much of the sediment was deposited above sea level in oxidizing conditions. The green colored members indicate a reducing environment characterized by frequent inundation by water either in a swamp, delta, or shallow sea. Later beds have frequent conglomerate beds signaling the first wave of the Alleghenian orogeny.[2]
[edit] Fossils
Plants from the division Pteridospermatophyta notably Adiantites have been identified. Some fish and worm burrows have also been observed.[3]
[edit] Age
Relative age dating of the Mauch Chunk places it in the Late Mississippian period, with some of the top layers in the Early Pennsylvanian Period, being deposited between 345 to 320(±3) million years ago. It rests conformably a top many formations. It's upper contact is complex. In certain areas, the contact is conformable in others, there is an unconformity. However, the Pottsville Formation is always above the Mauch Chunk.[4]
[edit] Economic Uses
[edit] References
- ^ Berg, T.M., Edmunds, W.E., Geyer, A.R. and others, compilers, (1980). Geologic Map of Pennsylvania: Pennsylvania Geologic Survey, Map 1, scale 1:250,000.
- ^ Wood, G.H., Trexler, J.P., Kehn, T.M., (1964). Geology of the West-Central Part of the Southern Anthracite Field and Adjoining Areas, Pennsylvania. United States Geological Survey, C-46.
- ^ Jennings, J.R., (1985). Fossil plants from the Mauch Chunk Formation of Pennsylvania: Morphology of Adiantites Antiquus. Joural of Paleontology, v 59 n 5, p 1146-1157.
- ^ Berg, T.M., et al., (1983). Stratagraphic Correlation Chart of Pennsylvania: G75, Pennsylvania Geologic Survey, Harrisburg, Pennsylvania.
