M - Mesozoic & Cenozoic Margin

The Mesozoic and Cenozoic Divergent Continental Margin 
Upper Jurassic, Cretaceous, and Cenozoic; 175 my - present

The record in the Atlantic continental margin record of the Atlantic seaboard is preserved in the Coastal Plain province and under water along the present day continental shelf. The record consists of a gently eastward-dipping, seaward-thickening wedge of sediments. The edge of the Coastal Plain sediments is the farthest western extent of the continental margin sediments, which cover both igneous and metamorphic basement rock and part or all of some Triassic rift basins. North of the Richmond and Taylorsville basins, for example, completely buried basins have been recently discovered.
Some stratigraphic units of the margin thin to a feather edge at the western edge of the Coastal Plain province, but other units originally extended farther west and have been since truncated by erosion. It is possible that during part of the Cretaceous all of Virginia was under water.
Coastal Plain sediments have a complex history as a result of both subsidence of the continental margin and fluctuations in sea level.  Sea level has been slowly rising over the past few hundred years, slowly inundating the exposed Coastal Plain. Large coastal storms, which cause erosion of the beaches and barrier islands, help to push beaches and barrier islands further and further inland as the sea transgresses again across eastern Virginia once again.
Contributed by Lynn Fichter 
Friday, August 24, 2018
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