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Now, what becomes of these vast quantities of detritus furnished to the sea? That depends on the shore currents at the particular locality. If there is not much of a current, the larger grains of grit and sand are soon separated from the rest, and fall to the bottom, whilst the clays are taken farther out to sea before being laid down. But, in any case, the reader will readily perceive that marine deposits must of necessity be on a grander scale, and of a much more substantial character, as a rule, than river, lacustrine, or estuarine deposits. By their mode of origin, too, they must be more homogeneous, whilst they are frequently several hundreds of feet in thickness. In their process of deposition they were not influenced by every storm and freshet; nothing short of great earth-movements in process of time, or some other equally grand phenomena, could disturb the even tenour of their existence. How different to the comparatively insignificant strata formed by the other methods alluded to!