Plate Tectonics

During the Ordovician Period, plate convergence caused the closing of the proto-Atlantic Ocean and a deep basin developed into which thick mud and dirty sand was deposited (to ultimately form shales and sandstones of the Martinsburg formation). With continued compression, the sediments were folded and faulted during the Taconic mountain building episode (Orogeny). Following this deformation, mountains rose to the east and coarse sediments were transported westward to form the Shawangunk conglomerate (massive bedded rock in photo). Thus the Taconic unconformity or hiatus (pictured in this image) in southeastern New York is about 20 to 30 million years, nearly as long as the entire Silurian Period itself.

Mohonk Preserve, Ulster County, NY

With support from the Center for Applied Technologies in Education, The Earth Science Digital Image Library is an initiative authored by Russell Agostaro, Newburgh Enlarged City School District, Newburgh, New York.

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