Lower Curtis Glacier extends from 5700 feet to 4900 feet. Viewed from
Artists Point, the glacier's low altitude is obvious as you seem to
look down on the glacier. The low altitude is a result of the
tremendous avalanche accumulation. The upper portion (eastern) of the
glacier has two large avalanche fans which are showered year around
with snow, ice and rock from the Upper Curtis Glacier. During the
summer the avalanches descend form Upper Curtis Glacier usually during
the heat of the day. Any sunny day an extended lunch break will
provide at least one small avalanche. The south side of the glacier is
fed by two avalanche chutes as well. Below the avalanche fans the
glacier has a minimal slope for a half mile to the lip of the cirque.
Despite the low slope this basin has numerous gaping crevasses, because
the glacier is moving rapidly due to heavy accumulation. The snowline
is in the middle of the flat basin at 5300 feet. The glacier pours
over the lip of the cirque in a spectacular array of seracs. Because
of the avalanche activity from Upper Curtis Glacier the center of the
Lower Curtis Glacier is loaded with debris. The steep terminus is
deadly to travel upon as the rocks carried on the surface melt out and
tumble down the surface.
Lower Curtis Glacier is pecuilar in that it has a series of waves
in the central portion of the glacier. The waves are 200-300 feet
apart and 25-40 feet high. The waves demonstrate that the glacier's
spped varies with time. Below the lip of the cirque the waves "break"
tilting farther and farther forward until collapsing. The front of the
glacier releases numerous rock and ice avalanches into the Shuksan
Creek Basin below.
Another pecuilar aspect of this glacier is that the annual
accumulation layers are quite distinct at the lip of the cirque, even
when viewed from Lake Ann. The thickness of the layers averages 5.5
feet, this is the average annual accumulation remaining at the end of
the summer. A total of 45 layers have been identified in recent years
suggesting that most ice within this glacier is less than 50 years old.
The velocity of the glacier at the snowline was observed from 1986 to
1989, the velocity is 145 feet/year.
Lower Curtis Glacier advanced dramatically during the 1960's and
1970's, from the lip of the cirque more than 400 feet down a steep
slope. The central portion of the terminus has been in equilibrium
recently, while the northern side of the glacier has retreated 48 feet
since 1985. The mean annual balance from 1984-1990 has been -0.9
feet/year; thus retreat will continue. On the north side of the
glacier a lateral moraine from the Little Ice Age is only 60 feet
beyond the recent lateral moraine indicating a limited Little Ice Age
advance.
Lower Curtis Glacier is one of the easiest North Cascade glaciers
to reach. From Austin Pass take the trail to Lake Ann, 4 miles. From
Lake Ann the trail continues for one mile to Fisher Chimney. Shortly
before the chimney, after crossing a steep talus draw, the main trail
ascends, and the old trail continues to traverse. Follow the old trail
across this steep slope, descending slightly. After several hundred
yards the trail switchesback in its descent to who knows where.
Continue traversing from here the remaining 300 feet to the glacier.
There are excellent viewpoints from the edge of the glacier, but this
is not a safe glacier to explore.