Conglomerates in New England Gneisses- — Hitchcock. 255 
base two masses of slate, each a half mile or more in length, 
but completely imbedded in granite. Adjacent to them is a 
breccia whose paste is hardly discernible, but gradually be- 
coming evident at the distance of several rods from the un- 
broken slate. The fragments gradually diminish in number 
though they are visible to the very top of the mountain. 
Upon Mt. Moat, across the valley, the slate fragments also 
abound. These examples belong to the class of ejections 
described by Dr. Hawes upon Mt, Willard, (Amer. Jour. Sci. Jan. 
1881.) where it is claimed evidences of igneous eruption are to 
be discerned in the formation of microscopic crystals of tour- 
maline, the increased amount of silica and other contact phe- 
nomena. The slate described is the same with that observed 
upon Mts. Pequawket and Moat. 
The specimen described by Prof. 0. P. Hubbard from War- 
ner [not Warren] in 1859 is now in the Dartmouth College 
museum. The so-called boulder seems to be of concretionary 
origin. Its mass is essentially the same with that of the en- 
veloping granite, but is separated from it by a thin coating of 
biotite which covers the oval interior just as the skin covers 
an apple. Had the inclusion ever been subjected to attrition 
the biotite would have disappeared. Being in the neighbor- 
hood of the curious mica nodules of Vermont its concretion- 
ary origin is still more apparent. The last case cited is that 
of pebbles in mica schist in E. Hanover described by Dr. 
Hawes. These are paleozoic, and if they have any bearing 
upon the Laurentian conglomerates lead to an entirely differ- 
ent conclusion from that Avhich you have advocated. 
In your note in connection with the Errata of the " separ- 
ates," you refer to the conglomerate in the Black Hills, as 
described by W. 0. Crosby and F. R. Carpenter. Both these 
gentlemen present facts showing the probable absence of the 
Laurentian from the Black Hills ; and the particular conglom- 
ate cited is correlated with the fossiliferous Taconic of western 
New England, also with the conglomerate of Bellingham, Mass., 
which may also be Cambrian, certainly post Laurentian. The 
point which I desire to emphasize is, that while your view 
of the Laurentian inclusions may be correct, there is no sup- 
port to your position to he derived from any of the cases 
cited from the East and the Black Hills. 
In my writings upon the granite of New England I have 
