QUATERNARY
SURFICIAL DEPOSITS
POST LAST GLACIATION
GLACIAL ENVIRONMENT
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ICE AND SNOW: Small alpine cirque glaciers and
semipermanent snowbanks |
NONGLACIAL ENVIRONMENTS
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ORGANIC DEPOSITS: organic matter; 1 to 2 m thick;
formed by the accumulation of vegetation in poorly drained depressions
(swamps and bogs) |
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COLLUVIAL DEPOSITS: active and inactive landslides,
undivided; mass wasting debris 1-100 m thick |
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FLUVIAL DEPOSITS: alluvium; sorted gravel
and sand >1 m thick; forming active flood plains A, and terraces
At |
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ALLUVIAL FAN DEPOSITS: poorly sorted gravel and
sand >1 m thick |
POSTGLACIAL OR LATE WINSCONSINAN
PROGLACIAL AND GLACIAL ENVIRONMENTS
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LACUSTRINE DEPOSITS: fine sand, silt, and clay,
deposited in glacier-dammed lakes; > 1 m thick; often overlain by organic
deposits in lowlands; level topography |
GLACIOFLUVIAL DEPOSITS: gravel, sand, minor sandy diamicton,
usually 1 to 40 m thick; deposited by meltwater behind, at, or in front
of glacier margins
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Proglacial outwash: gravel and sand deposited in front
of the ice margin forming distal outwash terraces Gt, or
undifferentiated G |
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Ice-contact glaciofluvial sediments: coarse sand and
gravel interbedded with discontinuous lenses of diamicton |
TILL: nonsorted debris deposited directly by glacial ice;
matrix is sandy to clayey and contains striated clasts of various lithologies;
mountain till is characterized by local rock types and/or with sparse erratics
transported westward from the Rocky Moutains; the plains and plateaus in
the east are covered by continental till containing many Canadian Shield
rocks
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Laurentide till blanket; > 1 m thick; forming undulating
topography that may be fluted and drumlinized in places; contains erratics
of eastern provenance |
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Cordilleran/Montane till blanket; > 1 m thick; forming
undulating topography that may be fluted and drumlinized in places; contains
erratics of western provenance |
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undifferentiated till veneer, < 1 m thick and discontinuous;
underlying bedrock topography is discernible |
PRE-QUATERNARY
BEDROCK
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Sedimentary bedrock. In the west, the Rocky Mountains and foothills
are characterized by Paleozoic to Mesozoic rocks forming longitudinal fault-
and fold-controlled mountain ranges and valleys trending northward . The
east is characterized by flat-lying Cretaceaous shales and cliff-forming
sandstone units. |