CLARK: TACONFC REVOLUTfONT. 153 
This paper is directly preceded by one by H. S. Williams en- 
titled, "On the Fossil Faunas of the Ste. Helen's Breccias." 
These two papers, in conjunction with Nolan and Dixon's 
article^ give in detail the geological phenomena as observed. For 
our purposes, however, the conclusion reached by Harvie is all 
that is required and is not open to question. 
Beloeil Mountain. — The only recent work upon the geology of 
this mountain is that by O'Neill.'- This gives a bibliography of 
papers on the region, and while we are not primarily interested 
in the historical aspect of the case, it is interesting to see how 
little has been written on the geology of this mountain. 
Beloeil Mountain rises from the St. Lawrence lowland and is 
surrounded by nearly flat-lying Ordovician rocks, which are 
here about 3000 feet thick. The highest member of this con- 
formable series is the Lorraine, which is found on the southeast. 
With regard to the mountain itself, which is composed largely of 
essexite and nepheline syenite, large blocks of limestone are 
found enclosed in the frozen magma, some of which are fossili- 
ferous. Ells is responsible for the statement that xenoliths of 
Devonian limestone have been found within the igneous rock, 
but, though he left a sketch map of the exact spot, these blocks 
have never since been found. It is obvious, of course, that in 
any event, their presence in the magma is utterly worthless as 
evidence of Taconic mountain-building. 
Hudson Valley. 
Becraft's Mountain was cited by Dana in the earliest edition 
of his Manual as one of three localities proving late Ordovician 
mountain-making. The latest publication on this locality is 
one by Clarke,'^ which includes a brief review of the previous 
opinions on the structure of the mountain. Since Mather's 
Report on the First District, it has been assumed that a well- 
defined unconformity existed between the Hudson shales and 
•Nolan, A. W., and Dixon. J. D. Geology of Ste. Helen's Island. 
Can. Rec. Sci, vol. 9, p. rv.\m, 1903. 
'^O'Neill, .]. •]. St. Hilairc! (Beloeil) and Rouf^emont Mountains, 
Quebec. Mem. (Jeol. Surv. (^anada, no. 4.}, pp. 10, 24, H)14. 
'Clarke, J. M. The Oriskany Fauna of Beeraft, Mountaiti. Mem. 
N. Y. State Mus.. no. .'}, vol. :?, UHM). 
