1893. ] NEW YORK ACADEMY OF SCIENCES. 109 
which enters the valley from the west. The thickness of the 
delta deposit is about forty feet, and the materials composing it 
are sand and cobbles up to six inches in diameter, these latter 
being mostly the different forms of norites and gabbros. At the 
base of this section is reddish clay. Barton Brook, which enters 
the extreme northwest corner of the valley, has also deposited 
considerable coarse material about its mouth. 
To sum up there was in Russian Valley a lake five miles long 
and one-half to one mile wide, and one hundred feet deep. The 
lake was caused by the formation of a dam of drift between 
Raven’s Peak and Wood’s Hill, which was gradually cut down by 
the Bouquet River, the outlet of the lake. 
Wecan at the present day see all the stages of transition from 
the lake, as originally caused by the dam of drift, to the flat- 
bottomed meadow or vly, the old lake bed. Lake Placid may be 
instanced as a lake formed by a wall of drift. Another is Long 
Pond, four miles south of North Elba. Itis about one thousand 
feet long, and lies in a narrow fault valley, its outlet being over 
a wall of drift at the north end. The first step in the oblitera- 
tion would be either the filling of the pond with sediment 
brought in by tributary streams or the cutting down of the out- 
let. These causes may be acting singly or at the same time. 
Lake-filling i is going on actively in many localities, and has been 
described in detail by Prof. Smyth, of Hamilton College, who 
has observed the filling of lakes in Hamilton county. 
Little Pond two miles northeast of New Russia is decr easing 
in size due to the formation of a swamp around its outlet. The 
streams flowing into Lincoln Pond two miles farther south 
haye brought in so much sediment that the pond is now only 
one-third its former size. Finally we have the lake completely 
destroyed and only a flat, swampy meadow is left, as in the case 
of Russian Valley and many others. 
CoLUMBIA COLLEGE, November, 1893. 
The paper was illustrated by lantern views. 
“On the Stratigraphical Relations of the Bed which yields 
the Triarthrus Beckii with appendages,” by W. 8. Valiant. 
Read by G. Van Ingen. 
“Notes on the Fossil Fish in the State Museum at Frankfort, 
Ky.,” by Dr Bashford Dean. 
* Amer. Geol., February, 1893. 
