Interpretive Cross Sections From Eastern West Virginia Across Northern Virginia Showing Deep and Shallow Taconic Facies Relative to Present Geology
Enlargement of bottom cross section below
Most of the time when we reconstruct geologic histories we use the present location of the rocks to make interpretations. That this is not always wise is shown by these cross sections.
The present location of foreland basin rocks for the Taconic orogeny implies the basins are closer together than they were originally. But we can get some idea of their true original locations from these Interpretive Cross Sections. The first (Pre-Taconian) cross section shows the Virginia divergent continental margin stretched out with all the subsequent folding and faulting undone. The second cross section (Taconian) shows development of the Western Cratonic and Eastern Flysch basins in the Taconic. The third (Alleghenian) cross section shows the present location of all the rock units.
Note the distance between reference arrows A and B. The third cross section (Alleghenian) shows how the rocks have telescoped together by folding and faulting. Note especially how the reference arrows A and B have moved close together, how the Eastern Flysch basin (dark green beds) has been thrust westward over top of the Western Cratonic rocks, and how most of the Western Cratonic basin rocks (yellow beds) extend far to the east below the surface.
by Lynn Fichter
Saturday, August 02, 2014