- A great part of the bottom of the Mediterranean is covered with blue muds, frequently with a yellow upper layer containing a considerable proportion of carbonate of lime, chiefly shells of pelagic Foraminifera.
The terrigenous deposits consist of blue muds, red muds (abundant along the coast of Brazil, where the amount of organic matter present is insufficient to reduce the iron in the matter brought down by the great rivers to produce blue muds), green muds and sands, and volcanic and coral detritus.
The coarser particles of the sediments are deposited near the shore as gravels, sand and muds, but the very fine particles remain in suspension in the colloidal form, and some of this may be acted upon by marine bacteria or (it is surmised) even utilized by diatoms as a source of silica.
Littoral Deposits (between high andSands, gravels, muds, &c. low-water marks) Kriimmel prefers to simplify this by grouping the deposits in a single category arranged according to their position into: (a) Littoral (including Murray and Renard's littoral and shallow water deposits [II.
De Pourtales pointed out in 1870; they consist of remains of deep-sea corals, serpulae, echinoderms and mollusca united Sands, gravels, muds, &c.