Lecture 36 (Wednesday, April 24, 2002): Geology of the Eastern US
Brief outline of this lecture:
Geologic Overview of the Eastern US
Origin of the Appalachians - Convergence
Origin of the Coastal Plain - Divergence
The Fall Line
The Eastern Interior
Main points of this lecture:
Georgia and much of the southeast can be divided into four geologic regions, the Coastal Plain, Piedmont, Blue Ridge, and Valley and Ridge.
The Coastal Plain consists of undeformed Cretaceous and Cenozoic sedimentary rocks and sediments.
The Piedmont consists of igneous and high-grade metamorphic rocks. Many of the igneous rocks formed about 300 million years ago.
The Blue Ridge consists mostly of metamorphic rocks.
The Valley and Ridge consists of folded and thrust-faulted Paleozoic sedimentary rocks.
The Fall LIne is the boundary between Piedmont and Coastal Plain. Because many rivers have shoals, rapids, or falls at the boundary, the Fall Line is a barrier to shipping, and therefore many cities lie along the Fall Line.
The Southern Appalachians are best explained as mountain range that formed in a continent-continent collision in the late Paleozoic.
The Coastal Plain developed after rifting of the supercontinent made in the continent-continent collision discussed above.
Much of the rest of the eastern US consists of an Eastern Interior of relatively undeformed Paleozoic sedimentary rocks.
Figures used in this lecture:
A generic cross-section through the Appalachians and Piedmont
A generic cross section through the Coastal Plain
The Fall Line in Georgia
The Fall Line in the eastern U.S.
A very simple geologic map of the eastern US, with labels
A very simple geologic map of the continental US, without labels
Reading assignment: None.
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