IV.—Disturbed Gravels

Extract

There are many features characterizing the surface portions of deposits which are very puzzling. Indeed, the more one studies them the less one is inclined to be dogmatic. Many true glacial deposits show remarkable signs of disturbance throughout their mass. We may instance the Contorted Clay of Norfolk as a case in point. Even when boulder-clays are too uniform in texture to show signs of movement they are often kneaded into the rocks upon which they rest, and rocks of all ages often show such disturbances when they have been overridden by ice. Here we are dealing with the results produced by the action of forces operating from without the deposit.