370 The Anicncan Geologist. December. i899 
reaching into the heart of the mountain regions of New Hamp- 
shire and Maine. In the spring, when the snows are melting, 
a vast body of water pours ofif the hills and the river becomes 
a fierce flood. The adjacent valley does not gather such a 
volume and its flood is restrained in the lakes and ponds. Thus 
it comes about that the river rises very rapidly, the lake slowly. 
Finally the slight difiference between lake and river level is 
overcome and a great flood of muddy water pours into the lake. 
Then the lake rises equally with the river till the flood has % 
reached its hight. With its waning the waters follow the sink- 
ing level of the river till the normal condition is resumed. 
So fierce is this reversed current that it has frequently swept 
away strong l)ridges and borne them toward the lake. The 
volume which rushes in, added to that which enters the lake 
at its head is sufficient to raise the lake about eighteen feet 
above its normal low-water level. So delicate is the adjust- 
ment that the opening of the dams at the Rangeleys, near 
the head of the Androscoggin, is sufficient to reverse the cur- 
rent in the Dead river and to raise the lake level many feet, 
even when conditions are otherwise normal. 
It is evident that such a flood of muddy water entering a 
basin, for the moment wholly inclosed, must leave behind a 
great mass of sediment. This sediment is not spread widely- 
over the floor of the lake, for the greater part of the bottom is 
remarkably free from nmd. Moreover it is noted that the 
muddy waters do not spread out above the clear water, nor mix 
with them, but rather appear to displace them near the point 
of in-rush. Thus the sediment is concentrated there. In con- 
sequence of this a well developed delta has pushed its way 
into the lake, having all the normal characteristics. The stream 
u'inds along between low flat nuul •l)anks which stretcli away 
on either side till they pass into shoals beneath the water. At 
present the water finds its w^ay out through twO' distributaries 
extending backward, while the former course of a third is well 
marked by a succession of pond-holes now partially filled up. 
With every flood the waters spread out over the surface and 
lay down a new layer. If, as sometimes happens, the Rangeley 
dams are opened after the grass is well grown upon the • 
meadows of the delta, the grit collects upon the blades in 
sufficient amount to play havoc with the farmers' scythes. 
