12 DIAT0MA* 



for one or two feet, is a yellow loam, and, at the bottom, is the 

 stratum, containing the diatornacea\ 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 microscop- 

 ists. 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 

 secured; so it is extremely desirable that those localities should 

 be again visited, the geological relations of the strata ascer- 

 tained, 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 consider- 

 ably under the name of "electro-silicon," as a polishing pow- 

 der. 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 contained in them, or in the strata 

 above or below them, should be gathered, and their position 

 noted on the labels accompanying them. All specimens should 

 be kept carefully separate (not even permitting them to come 

 in contact) by wrapping each one in paper, placing within a 

 label having written upon it in ink the exact locality, date of 

 collection, and name of collector. It is also desirable that note 

 should be made of the depth from the surface at which the 

 specimen was taken, together with any other information that 

 may be deemed of interest, as supposed extent of stratum, 

 slope-upwards towards north, south, east, or west, and thick- 

 ness. 



Lacustrine Sedimentary Deposits. These were called by me at 

 one time sub-peat deposits, from the fact that all I had seen np 

 to that time had been discovered beneath peat; but as the num- 

 ber of these strata which have come into my hands has in- 

 creased, I have seen many which do not occur under such 

 circumstances; hence the above name has been applied to them 



