CHAPTER XIII 
DEPOSITION IN THE SEA 
General View. — While during the movement of rock 
material from land to sea, some finds temporary lodge- 
ment on the land, in river valley or lake basin, most 
goes to its goal, the sea, where it is spread out over 
the ocean bottom. The sea is supplied with mate- 
rials for sedimentation (1) by the wind which blows 
particles from the land, (2) by the rivers and (8) gla- 
ciers, which move over the land, (4) by the waves that 
beat against the shores, and (5) by volcanoes, which 
send showers of ash and pumice into the air. 
Most of the supply is in the form of fragments which 
are transported by mechanical means; but much is fur- 
nished as chemically dissolved mineral material. This 
latter may be accumulated in beds directly by precipi- 
tation, or it may be taken out of the water by animals 
or plants, and thus be deposited by indirect means. 
Therefore on the sea bottom, we have formed sedi- 
mentary rocks of three kinds, mechanical, chemical, and 
organic (pp. 71-98). The former are by far the most 
important, the chemical sediments are least in quantity. 
243 
