GLACIER NATIONAL PARK
(photos from the textbook CD)
St. Mary Lake at Wild Goose Island overlook, Glacier National Park, Montana,
USA. This is probably the most stereotypical scenery and most
photographed spot in Glacier National Park. Notice the U-shaped valley,
carved by Pleistocene-aged mountain glaciers (valley glaciers/alpine glaciers).
Notice the layered sedimentary rocks in the mountains - part of the Belt
Supergroup, a Proterozoic-aged rift valley fill. The portion of the
American Rocky Mountains having layered sedimentary rocks is called the Northern
Rocky Mountains Physiographic Province.
Cirque
and hanging valley and waterfall in Glacier National Park. Note the
U-shaped valley of the cirque. Notice the aretes (knife-like ridges at
the margins of the cirque).
Grinnell Glacier & diorite sill (above & below) - the Grinnell Glacier terminates
in a small lake. The rock wall behind Grinnell Glacier has sedimentary
rocks of the Belt Supergroup intruded by a diorite sill. The whitish zone
above & below the diorite sill is a bleached zone, the result of contact
metamorphism.
Cirque
and hanging valley. Note the diorite sill and bleached zone in the
distant rock wall to the left of center.
U-shaped valley carved by mountain glaciers (a.k.a. valley
glaciers; a.k.a. alpine glaciers) during the Pleistocene Ice Age.
Horn
- a pointed, peaky mountain top formed by glacial erosion and the development
of multiple cirques.
Mudcracks preserved in reddish, hematite-rich argillite (slightly metamorphosed
shale) of the Grinnell Formation (Belt Supergroup, Proterozoic). Mudcracks
form under alternating wet and dry conditions.
GLACIER NATIONAL PARK
(photos from JSJ)
Till
- Pleistocene-aged glacial till in roadcut outside Glacier National Park,
Montana, USA. Till consists of poorly-sorted, coarse-grained,
poorly-bedded to nonbedded glacial deposits. With burial and
lithification, till deposits become glacial conglomerates, or tillites.
Diorite sill (dark rock at bottom) intruding Belt Supergroup sedimentary rocks at
Big Drift roadcut along Going-to-the-Sun Highway.
Light-colored rocks at center & top = bleached
zone from contact metamorphism.