216 TRANSACTIONS OF THE [WAX 2, 
river. and show a prevailingly northeasterly dip at a low angle, 
disappearing beneath the drift valley. The valley is underlain 
by blue clay of the Champlain period, and extends in a band 
two to three miles wide through both townships. On the east- 
ern side of this area appears first the Chazy, of two sets of lime- 
stone beds, then the Trenton, usually as a shaly limestone, 
finally the Utica shales, exclusively along the shore. All the 
foregoing formations are cut by numerous diabase and porphyry 
dikes. Altogether we have presented a remarkably diversified 
and prolific field for geological study within a limited area. 
ARCHZAN. 
The Archean of the two townships comprises the following’ 
First, the labradorite rocks, gabbros, norites and anorthosites, 
forming the whole western district and giving rise to the typical 
“tri-mountain” variety of hills noted by Emmons.* On the north 
they terminate the range that traverses the townships to the 
westward and end abruptly in cliffs two hundred feet high on 
Willsboro’ Bay. The labradorite rocks on the south extend to 
the Split Rock Range of Westport. Second, the metamorphic 
crystalline limestones and ophicalcites on Willsboro’ Bay and 
the ridge of Split Rock Point. Third,the gneisses and granites 
chiefly of the latter locality. We have adopted the classifica- 
tion of Adams in placing all these in the Laurentian.t 
Van Hise{ advances the theory of a central core of gabbro, 
with surrounding gneissic series of limestones, schists, ete., be- 
longing to the Algonkian, “the metamorphism having been pro- 
duced by the great laccolites or batholites of gabbro.” 
The labradorite rocks,as termed by Redfield,§ or ‘ hypers- 
thene rock,” by Emmons,|| and also called ‘‘ hypersthene fels,” 
etc., vary greatly and blend imperceptibly into one another. By 
comparison of fifty odd specimens from both townships, I am 
unable to trace any definite geographical or other sequence cor- 
responding to the variation. 
The basic gabbro is the prevailing type. Usually it exhibits 
a yellowish kaolinized feldspar, resulting from its ready 
*E. Emmons: Rept. on Second District, pp. 232-233 (1837). 
+See complete discusson by Pror. J. F. Kemp: Gabbros of the Western Shore 
of Lake Champlain; Bull. Geol. Soc. Amer. V.: 213-224, particularly page 214, 
and for summary of previous theories, the same writer in A Review 0 the work 
hitherto Gone on the Geology of the Adirondacks, Trans. N. Y. Acad. Sci., XII.: 
19, (1892). 
{C. R. Van Hise: Correlation Papers, Archean and Algonkian, Bull. 86, U. S. 
G.S., pp. 413, 516, 495, ete. 
§ W. C. REDFIELD: Some account of two visits to the mountains of Essex Co., 
N.Y. Am. Jour. Sci. Ser. 1: XXXII-.: 301 (1837). 
|| E. Emmons: Rept. on Second District of New York State, 1842, etc. 
