Geology has thrived on the application of the maxim, the present is the key to the past. Investigation of the phenomena and active processes of the surrounding world has proved to supply the most trustworthy foundation for interpreting the features of ancient rocks and unravelling the geological history of the earth's crust. But one chapter of geology has formed an exception, that of ancient marine sediments. Considering the extent as well as the economic and paleontologic importance of these rocks, it is a huge chapter. In this domain geologists have attempted the opposite procedure, namely to deduce the submarine processes from the features of their consolidated rocks.