GLACIAL PHENOMENA IN THE ADIRONDACKS 411 
Lawrence, Champlain, and Hudson drainage. The principal 
Adirondack rivers—Raquette, St. Regis, Saranac, Ausable, 
Boquet, Schroon, Boreas, and Indian—are alike in that their 
sources lie in chains of lakes which owe their origin to glacial 
agencies. The stream profiles are convex, indicating a young 
drainage. The lower courses consist of series of still waters, 
separated by falls or rapids, the whole system owing its char- 
acter to) the occasional wearing off of the drift. Cushing 
describes several falls with still waters above and below, whose 
existence is due to the postglacial uncovering of hard ledges of 
rock. Obviously any rock is harder than drift, and such a dam 
and fall will be found wherever any bed rock is uncovered. On 
the inlet to Paradox Lake is such a fall over crystalline lime- 
stone of the Grenville series, which is the softest rock of the 
region. Obviously these falls are temporary, and will be worn 
back into gorges accompanying a draining of the lakes, until a 
mature and concave profile is produced. 
Lakes.— Lakes of various origins are present in the Adiron- 
dacks, and their study would well repay more careful investiga- 
tion than has yet been given them. They are commonest along 
the headwaters of rivers, and are here usually due to some form 
of drift filling in an old valley. Many other lakes, and those 
notably the smallest, occupy rock basins. Cushing observes that 
none such have been found in Franklin county, though he admits 
the possibility that certain lakes may belong to this category. 
In the southern Adirondacks rock basins are by far the common- 
est type; here they are usually associated with faulting, but the 
smoothed nature of their bounding rocks, and the frequency of 
scorings, suggest the possibility that ice erosion may have been 
at least a partial factor. 
The western gneissic area of low relief and gentle slopes is 
pre-eminently a land of lakes. They often occur in chains, 
connected by short stretches of river. The divides are low and 
usually of drift. These series of lakes represent broad pre-- 
glacial river valleys, locally deepened and widened by the ice 
during its advance, and filled with water-deposited drift during 
