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Glacier National Park

 

 

Glacier National Park from Apgar Lookout

Tri-Continental Divide:  the point that divides the flow of water to the Atlantic, Pacific and Hudson Bay.

 

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Logan Area Waterfall

 

     

Trip Details:

 

Glacier National Park 

August 5-8, 2005

Entered through the St. Mary side of the Park.  Drove the Going to the Sun Highway.  

Day 1:  Stopped at St. Mary's Lake, viewed Sunrift Gorge (too little light to photograph), hiked down to St. Mary's Falls by Sunrift Gorge Trail and to Gunsight Lake.  St. Mary's Falls is 30-40 waterfall in thick deep spruce forest of ferns and broadleaf plants.  AT St. Mary's Lake to Gunsight the terrain shifts to alpine tundra grasses with daisies, honeybuckets and a predominant white multi- rod flower (pictured to side).  Sedimentary rock craved by fast stream and waterfalls yield fossils in every rock.

  Day 2:  Logan Visitor Center:  Hiked to Hidden Lake.  Mountain Goats graze along the trail and sleep in cool snow-banks and are indifferent to humans allowing approaches to within feet.  Hidden Lake is a small mountain lake amount sharp buttes craved by glaciers.  Prime wildflower season was first week in August.  Trial to Hidden Lake is more of a walkway than a trail and is busy with sightseers. 
 

Day 3:  The Weeping Wall and other waterfalls cascade over the roadway and cars during the spring but were tired of crying by August affording a small spray.  I do not know of any waterfalls over roadways such and this and imagine the sight to be spectacular during the runoff season.

 

 

 

 

 

 

 

 

 

Indifferent Mountain Goat

Day 4: Lake McDonald:  Avalanche Gorge and Avalanche Lake are a short hike from the roadway.  McDonald stream follows the road out of the park and provides many stops and fishing opportunities.

Geological point of interest: Example of terminal and lateral morraines that blocked McDonald Creek and formed these high mountain lakes.  The terminal is pronounced at Lake McDonald.  

 

 
 

Lake McDonald is the largest lake in Glacier National Park. The Continental Divide follows the crest of the mountains visible in the background. Clouds blocked by the mountains drop considerable rainfall in this part of the park providing perfect growing conditions for forest species much more typically found on the Pacific Coast, like western red cedar and western hemlock.

 

 
 

St. Mary's Falls

 
   
 

Glacier preserves over 1,000,000 acres of forests, alpine meadows, and lakes. Its diverse habitats are home to over 70 species of mammals and over 260 species of birds. The spectacular glaciated landscape is a hikers paradise containing 700 miles of maintained trails that lead deep into one of the largest intact ecosystems in the lower 48 states.

The park contains over 350 structures listed on the National Register of Historic Sites and six National Historic Landmarks.

In 1932 Glacier and Waterton Lakes National Park, in Canada, were designated Waterton-Glacier International Peace Park. This designation celebrates the longstanding peace and friendship between our two nations. Glacier and Waterton Lakes have both been designated as Biosphere Reserves and together were recognized, in 1995, as a World Heritage Site.

 

 

 
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Going to the Sun Road near Logan.

 

St Mary's Lake on way to Gunsight

 

St. Mary's Falls

Iceberg Lake

 

 

my Links

Glacier National Park:

National Park Service: http://www.washingtonsuitesgeorgetown.com/http://www.nps.gov/glac/

Glacier Text: http://www.uwosh.edu/faculty_staff/hudak/Lecture_29_Notes.pdf 

 

Glacial Erosion
• Plucking
– Pieces of the underlying rock
are removed by the glacier due
to “freeze and thaw” in cracks
• Abrasion
– Pieces of rock frozen into the
glacial ice scratch/groove the
bedrock
– Glacial Striations: linear
scratches in bedrock which
can be used to tell flow
direction
– Rock Flour:very finely ground
rock (silt/clay size) caused by
extreme grinding of materials
from glacial movement

 
Zones in Glacial Ice (cont.)
• Crevasses
– Open cracks (fissures) in
the glacial ice caused by
tensional (extensional)
forces as the ice flows over
an area where the valley
floor steepens
• Icefall
– A jumbled mess of chaotic
blocks where long, steep
valleys are present
 
Valley Glacier Erosional
Landforms
• Glacial Valleys
–U-shaped in cross-section
(not V-shaped like streams)
– Hanging Valleys: occur
where tributaries flow into
main valley
– Tend to be straight
– Rock basin lakes (tarns)
may form
– “Rouche Moutonnee” =
Rounded resistant knobs
that form parallel to ice
flow

 

 
Valley Glacier Erosional
Landforms (cont.)
Cirques, Horns, Aretes
• Cirque = steep-sided halfbowl
shaped recess carved
into a mountain at the head
of a valley glacier
• Horn = sharp peak that
remains after cirques have
cut back a mountain on
several sides
• Arκte = sharp ridge that
separates adjacent glacial
valley (knife’s edge ridges)
Continental Glacier Erosional
Landforms
General Observations
• Continental ice sheets tend
to produce gently-rounded
topography
• Most common evidence of
erosion are:
– Glacial Striations
– Roche Moutonnee
• Outcrops tend to be rounded
and scratched
 
 
Materials Carried in a Glacier
• Ice sheets carry mainly
materials scraped / plucked
from the underlying bedrock
– These materials commonly
transported near the base of
the glacier
• Valley glaciers carry this type
of material, as well as
materials that fall off of the
valley walls
Materials Carried in a Glacier
(continued)
• The materials carried by the
glacier tend to be:
– Angular, unweathered,
unsorted (clay to boulders)
– Derived from sources
underneath the glacier
• Erratic = a large boulder
carried / deposited by a
glacier
• TILL: Unsorted materials with
angular, unweathered
fragments carried and
deposited by a glacier.

 

 
Glacial Depositional Landforms
• Morraine = body of unsorted
glacial debris (till) carried on or
within a glacier that is left
behind when the glacier
recedes.
• 4 types of morraines:
– Lateral Morraines = elongate
mounds of till formed along
the side of a valley glacier
– Medial Morraines = single,
long mounds of till formed by
the coalescing of lateral
morraines (looks like highway
lanes on top of glacier)

 

Glacial Depositional Landforms
–End Morraines = a curved
ridge of till that forms at the
front edge of a glacier
• Terminal Morraine = marks the
farthest advance of the glacial
ice (only 1 per glacier)
• Recessional Morraine = forms
while the front edge of a
receding glacier remains
stationary (can build many)
–Ground Morraines = a thin
blanket of till carried within
the glacier and deposited
when the glacier melts
• Very gently rolling unsorted
glacial deposits

 

 
Glacial Depositional Landforms
– Eskar = sinuous ridge of
sediment deposited in tunnels
within or underneath glaciers
where meltwater flows under
and out from ice.
– Kettle Lake = a lake formed
when a block of stagnant ice
contained within till (or
outwash) melts
– Drumlin = streamlined
deposits of till shaped like
inverted spoons aligned
parallel to ice movement
• Gentle slope points in direction
of movement
Types of Glacial Deposits
– Till: see above
–Outwash = material deposited
in the zone of wastage by
debris-laden glacial meltwater
• Well-sorted, well-layered,
commonly cross-bedded
• Can be extensive sheets
–Loess = very fine-grained
ground-up rock (rock flour)
that gets re-deposited
(generally by wind) to form
rich soils
 
Glacial Lakes
• Commonly form in front of a
receding glacier, or in the area
between a retreating glacier and
a morraine
Depositional Structures
in Glacial Lakes
• Varves = two thin layers of
sediment, one light-colored and
course grained, one dark
colored and finer grained,
believed to represent 1 years
deposition in a lake
• Dropstones = pebbles that fall
into varved sediments – cause
downward warping of layers

 

Effect of Glaciers
• Laurentide Ice Sheet
– 18,000 – 8,000 years ago
– Continental glacial event
– Dated using 14C
• Scraped away much of the soil
in southern Canada, dropped
vast amounts of till / outwash in
northern and central US
• Most tills were deposited as
ground morraines
– Excellent soils for agriculture
• Great Lakes, in part, thought to
represent valleys of soft
sedimentary rocks gauged-out
during glaciation

 

 
Effect of Glaciers
• Many of the lakes in Wisconsin,
Minnesota, Michigan, and
Ontario were formed as the
result of glacial activities
• Currently northern part of US is
undergoing isostatic rebound
(crust is slowly rising due to
absence of thick (up to 2 miles)
mass of glacial ice
• In western US / Canada, valley
glaciation that occurred at the
same time as Laurentide Ice
Sheet is called the Cordilleran
Ice Sheet

 

Causes for Glaciation
• Oldest glaciation = 2.3 billion
years ago (Gowganda
Formation, Ontario)
• NO SATISFACTORY
EXPLANATION TO DATE
– Variations in the earth’s orbit to
the sun (change in solar radiation
due to change in angle changes
weather)
– Changes in the atmosphere
(atmosphere has the ability to filter
out solar radiation, it gets cold)
– Snowball Earth Hypothesis – earth
freezes 500-1000 MA due to lack of
CO2 in atmosphere – volcanic
activity over large period of time
provides CO2 to atmosphere to
unfreeze earth

 

   

 

 
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