MECHANISMS FOR STRAIN WITHIN THE UPPER DEVONIAN CLASTIC SEQUENCE OF THE APPALACHIAN PLATEAU, WESTERN NEW YORK.

The axial ratios of deformed crinoid ossicles within the clastic rocks of western New York indicate more than 15 percent layer-parallel shortening normal to fold axes on the Appalachian plateau (Engelder and Engelder, 1977). Using Groshong's (1972) calcite strain gauge technique, compressive strain accompanying calcite twinning is shown to account for 1 to 5 percent layer-parallel shortening or less than half the compression indicated by the axial ratio of the ossicles. This study concludes that cleavage-forming pressure solution is a more important mechanism than intragranular deformation for layer-parallel shortening on the Appalachian plateau.