Ijcike Filling in the Adirondack Region. — Smyth. S7 
inspection shows that it is chiefl}^ composed of glacial material, 
its original extent having been somewhat increased by the growth 
and decay of marsh plants. 
One mile and a half northeast of Wilmurt, lies Big Rock lake ; 
about equal to Wilmurt in size, but much more irregular in out- 
line, the rocky shore being indented by several small baj's. The 
erosion valley occupied by the main body of the lake extends 
nearly east and west, while a large arm or bay swings off in a 
northerly direction. This bay differs from the main body of the 
lake in that its shores are very steep, almost vertical, running 
down into thirt}^ or forty feet of water. Five rods west of the 
shore is a vertical cliff' of brown gneiss, and still farther west a 
deep ravine with vertical walls and no flowing water through it. 
The valley occupied by the northern arm of the lake is extended 
a mile or more by a similar ravine. The whole topography sug- 
gests that this portion of the lake basin is not the result of ero- 
sion alone, but owes its existence in part to orographic move- 
ments. 
Big Rock lake lies one hundred and (ifty feet lower than Wil- 
murt; and receives the drainage of a larger territority. Several 
streams flow into it bringing with them a considerable amount of 
sediment, which has had a marked effect upon the outline of the 
lake. This is most noticeable on the southern side, where the 
two largest and swiftest streams empty. One of these has filled 
a shallow ba}' and built out a little into the lake. The other has 
almost wholly filled a long narrow bay, whose original s,hores are 
sharply defined. The area formerly covered by water is now a 
level, marsh}' meadow; its surface about a foot above the ordi- 
nary level of the lake, and covered with a heavy growth of 
grass and a few small balsams and tamaracks. Through this, 
meadow the stream that has built it flows slowly, in a sinuous 
course. 
At Wilmurt, in the shoaling of the water about the mouths of 
streams, with the attendant growth of water and marsh plants, 
is illustrated the veiy earliest stage in the developementof a vlyj 
in this Big Rock Meadow is shown completed a portion of a vly 
which will ultimately occupy the place of the whole lake, unless, 
there shall be some disturbance of the forces now acting. 
The next stage in the series is shown in Little Rock and Sna*^ 
lakes, the former two miles west of Big Rock, the latter one milc; 
