Places like the American Southwest have remarkable rock formations produced by the erosion of sandstone and other substances, dramatically demonstrating the way deposited materials form layers of rock. In Vermont, the calcium from the creatures in a former sea, which has shrunk to become Lake Champlain, has become layered limestone and marble. The long geological history has included volcanic activity and glacial pressure and deposition. So the boulders display a variety of linear features. Under the heading “striation” I have included various types of layering, some of which involve curvature.