SUBMARINE DEPOSITS. 273 



The sounding's of the Fish Commission between southern 

 New England and the latitude of Chesapeake Bay were not 

 carried ou at a sufficient distance from the continental shelf to 

 reach the limits of the red clay. Even in the deepest sound- 

 ings, the globigerina ooze was still quite impure, being always 

 more or less mixed with sand and clay mud. In a number of 

 localities, the bottom between 500 and 1,200 fathoms consisted 

 of • tough and compact clay, of which large angular masses, 

 weighing more than fifty pounds, were brought up in the trawl 

 by the " Albatross." ^ In other localities, in 1,000 to 1,600 

 fathoms, the bottom appeared to be covered with flattened crust- 

 like concretions of clay, containing iron and manganese oxides, 

 these masses affording a foothold to many moUusks which could 

 not exist on softer bottoms. Similar points of attachment are 

 provided by the scattered boulders and pebbles found by the 

 Fish Commission at many points on the inner edge of the Gulf 

 Stream. These have probably been transported off shore by 

 floating ice. 



The explorations of the " Blake " and of the Fish Commission 

 off the New England coast were not carried on much beyond 

 the foot of the continental slope, where it passes into the west- 

 ern Atlantic basin. Only a portion of this region lies outside 

 of the limits of the disturbing forces due to the action of waves, 

 currents, and tides, w^hich, as is known, extend to a distance of 

 from two hundred to two hundred and fifty miles from shore, 

 and perhaps to a depth of nearly three hundred fathoms. 



Off the southern coast of New England, concretions of vary- 

 ing sizes were dredged by the Fish Commission in 640 fathoms, 

 the largest weighing* sixty pounds or more. They were com- 

 posed of grains of siliceous sand cemented by calcareous mat- 

 ter. In some cases the casts of foraminifera could be identi- 

 fied, or fossil shells distinguished that were identical with recent 

 species. Professor Verrill thinks these deposits may be of plio- 

 cene age, and that they probably form a part of the extensive 



1 Accorcllng to Professor Verrill, this age of the material. Similar deposits 



clay was mixed with more or less sand, were found by the " Blake " somewhat 



showing grains of quartz, feldspar, and farther north ; they contained, however, 



mica, tests of globigerinai and other fora- a larger proportion of foraminifera. 

 minifera making up but a small percent- 



