The portion of the Front Range of Colorado
between James Peak and Longs Peak was extensively glaciated
during the Pleistocene period by valley glaciers
whioh extended from near the continental divide down the
valleys of South Boulder Creek, Middle Boulder Creek,
North Boulder Creek, South St. Vrain Creek, Middle St.
Vrain Creek, and North St. Vrain creek for an average
distance of twelve miles. The glaciers were valley
glaciers except in the region northwest of Ward, where
the South St. Vrain glacier and the Middle St. Vrain
glacier coalesced to form a piedmont glacier which
covered between five and six square miles. Evidence
is presented to prove the existence of two periods of
glaciation. This evidence consists of (a) difference
in the degree of weathering of the morainal material of
the two periods, (b) the presence of morainal material
at different topographic levels and, (c) the development
of such topographic features as tandem cirques, 'hanging
cirques', and the existence of one glaciated valley within
another, land forms which can only rationally be explained
as the result of two periods of glaciation.