978 The American Geologist. April, 1892 
will be seen that I was considered responsible for most of the nomencla- 
ture of rocks mentioned in that volume, and that the results were not 
then fully published. At that time I was an assistant to professor Whit- 
ney, and therefore, with his other assistants, am held responsible by Mr. 
Fairbanks for the view which he has quoted. The results of my work 
were published in 1884, for the peridotities, in my “Lithological Studies.” 
In this work there were described more or less altered peridotites or ser- 
pentines from Colusa county, in the Coast range, and from Inyo, Sierra, 
and Plumas counties in the Sierra Nevada. All these described speci- 
mens were considered to be more or less altered forms of peridotite, in 
proof of which eight colored lithographic figures were given. (See my 
* Lithological Studies,” pp. 129-182, 142, 158, 189-192, plate 5, figures 1, 2, 
3; plate 6, figures 3, 4,5, 6; plate 7, figure 1.) It was also then stated 
that the microscopic and lithological characters of the Coast range peri- 
dotite and serpentines studied, as well as those from the Sierra Nevada, 
indicated that they are eruptive. I may also say that, so far as the 
specimens described by myself were concerned, the results obtained by 
me were accepted by professor Whitney in 1882 as satisfactory and con- 
clusive. As I have never studied any serpentine that I considered other- 
wise than derived from the alteration of peridotite or some allied erup- 
tive rock, Mr. Fairbanks’ confirmatory observations are of very great 
interest to myself. M. E. Wapswortn. 
Michigan Mining School, Houghton, Mich., March 2, 1892. 
ENGLACIAL DRIFT OF LONG IsLAND. In the December number of the 
AMERICAN GEOLOGIST, Warran Upham calls the attention of glacialists 
to certain criterea of englacial and subglacial drift. 
In my study of the drift formations of Long Island, I had noticed a 
difference between the bottom and surface portions of unmodified till, 
but was never able to draw a line between them. Of course, when the 
two were separated by a layer of stratified material, the surface part 
could easily be recognized from the hardpan, but where this line of 
separation does not take place it is difficult to determine exactly where 
the one leaves off and the other begins. It is true,as Mr. Upham re- 
marks, that the upper drift is yellowish in color, and is looser in texture 
than the hardpan, but the two blend into each other in such a way as to 
render a distinct separation impossible, and yet I am inclined to think 
that they are two distinct formations. One was laid down probably 
when the glacier advanced; the other was deposited when the ice-sheet 
retreated. The surface drift is variable in depth, and there are sections 
where it is absent altogether or is only represented by a few large 
boulders: as at Rockhill, near Eastport, Long Island, where a huge 
erratic is seen resting on the stratified gravel, the finer material having 
been washed away. In general, however, this yellowish sandy boulder 
drift covers the surface of Long Island. It covers the hills as well as 
the depressions at Brooklyn, and large niggerheads are everywhere seen, 
where the lots are vacant, protruding out of the drift which is only a few 
feet in thickness. Along the line of the terminal moraine it is very much 
