SUBMARINE DEPOSITS. 261 



The constant working over of the loose material by the waves 

 and currents along every part of the coast line is repeated on a 

 larger scale upon the continental shelf of our Atlantic coast. 

 There the results depend, not only on the nature of the materi- 

 als of the adjoining coast, but also upon the distance from shore, 

 the depth, the slope of the coast, and the character of the bot- 

 tom, and of the animals and plants living upon it and in the 

 surface waters. 



Mr. Murray ^ of the " Challenger " has paid special attention 

 to the bottom deposits, and we draw freely from his papers 

 in the sketch which we give of the various kinds of bottoms he 

 has recognized, as well as of the interesting views he holds on 

 the nature and origin of oceanic deposits. The subject as a 

 whole was first treated by Mr. Murray, to whom in connection 

 with the Abbe Renard we owe a connected sketch of deep-sea 

 formations. 



Our knowledge of marine deposits was formerly limited to 

 those of shallow waters. Attention was paid only to specimens 

 which could be collected by the Stellwagen cup, commonly used 

 for inshore hydrographic purposes. Our older charts contained 

 at best only meagTe information regarding the most character- 

 istic shore deposits. From the study of these we were able to 

 obtain a general idea of the nature of deposits on the inshore 

 plateau of the continental shelf, derived from materials con- 

 stantly subjected under very special conditions to the action of 

 the tides, waves, and currents. We could of course find no clue 

 to the conditions under which deposits were taking place in the 

 immense abyssal basins, thousands of miles in extent, that occupy 

 certain areas both in the Pacific and Atlantic, far away from any 

 continental mass. As soon, however, as samples of the bottom 

 were obtained from these great depths, a new chapter was 

 opened in thalassography. An examination of these samples 

 has given us the first comprehensive sketch of deep-sea deposits. 



1 JVIr. John Murray, to whom the spe- the shores of the Greater and Lesser An- 



cimens of bottom deposits collected by tilles ; and, finally, from the Gulf of 



the " Blake " were sent for examination, Mexico and Straits of Florida. Analyses 



has described in detail some typical spe- of the characteristic deposits will be found 



cimens from the coast between the Gulf in the Bulletin of the Museum, Vol. X. 



of Maine and Cape Hatteras ; between No. 2. 

 Cape Hatteras and Lat. 31° 48' N. ; from 



