480 



PHYSICAL GEOGRAPHY. 



Algeria, Africa, and at ^gina and Caltanisetta in Greece, are deposits 

 containing the remains of diatomacese intermixed with polycystina and 

 foraminifera, and referred to the Cretaceous. In the island of Barba- 

 does are so-called marls made up of diatomacese and polycystina, the 

 latter in great numbers and very beautiful. In the island of Trinidad, at 

 South Naparima, a similar stratum has lately been discovered which "is 

 considered as connected with the new red sandstone ; adjoining to which 

 is the sandstone, probably of the same description, in which the Pitch 

 lake is situated." At Moron, in Spain, has been found a similar deposit 

 of marine diatomaceae; and still another was discovered by Dr. C. F. 

 Winslow at a point about seventy miles south of the town of Payta, in 

 Peru, and about fifteen miles from the Pacific ocean. Here is a plain 

 separated from the sea by a range of hills several hundred feet high. 

 Within the plain is a depression with nearly perpendicular walls two 

 hundred feet high, the bottom of which depression is at about the level 

 of the sea — perhaps a little lower. The surface of the soil thereabouts 

 is covered with salt. For fifteen feet down there is a deposit containing 

 recent shells, the bones of cetacea, and pebbles; then, for one or two 

 feet, is a yellow loam, and, at the bottom, is the stratum, containing the 

 diatomaceae, which is from two to four feet thick. The amount Dr. 

 Winslow brought away was very small, and this is all that has got into 

 the hands of microscopists. Prof. Pumpelley brought from near Netanai, 

 in Japan, specimens of a like deposit. Very small fragments of the 

 strata from Jutland, Trinidad, Moron, Payta, and Japan have been se- 

 cured ; so it is extremely desirable that those localities should be again 

 visited, the geological relations of the strata ascertained, and a plentiful 

 supply of the material gathered. The sub-plutonic deposits seem to be 

 confined to the Pacific coast of the North American continent, and near 

 by. At Five-mile canon, near Virginia city, Nevada, is an enormously 

 thick stratum of this character, which is ground and sold considerably 

 under the name of "electro silicon," as a polishing powder. At Klamath 

 lake, on the banks of the Columbia and Pitt rivers, and elsewhere, at 

 many points, these deposits have been found. 



The rules already given hold good with regard to gathering specimens 

 of all of these deposits. Everything that can be ascertained with regard 

 to their position and relations should be noted. Also, any fossils con- 



