Table 1. Characteristics of surficial deposits.
Deposit
Materials
Topography and origin
Well bedded and well sorted
Smooth, with slopes nearly flat to very gentle; steep scarps
Alluvial
gravels and sands of variable
locally separate deposits at different levels; deposits from
thickness (few to tens of meters).
active streams and floodplains.
Clasts are rounded to well rounded.
Alluvial fan
Conically shaped with slopes moderate to gentle, steeper near
the fan apex.
Mainly loose, coarse rubble and
Smooth, with slopes generally steep to very steep and gener-
Colluvial
rubbly diamicton, locally bouldery.
ally unstable; deposits that accumulate on a slope primarily
poorly bedded and sorted through the action of gravity and
secondarily with the aid of water.
Features or deposits associated with glacial streams.
Glacioalluvial
Kame
Chiefly pebble and cobble gravel and
Sharply hilly to hummocky with some local depressions;
sand, moderately to well bedded, in
slopes moderate to steep; glacioalluvial deposit formed
places chaotically.
by running water within a glacier during early stages of
stagnation and modified during ice meltout.
Kame-terrace
Chiefly pebble and cobble gravel and
Long, narrow landforms that have smoothly sloping surfaces
sand, moderately to well bedded and
with prominent scarps on their downslope sides; glacioalluvial
sorted.
deposits formed by water running along the side margin of a
glacier.
Kame-channel
Chiefly pebble and cobble gravel and
Slightly hummocky in broad, channel-like landforms of low
sand, locally may include some finer
relief; glacioalluvial deposits formed in ice-contact channels.
materials.
Meltwater-
Chiefly gravel and sand, well bedded
Smooth with gentle slopes; channel-like deposits formed
channel
and sorted; surface may include finer-
in areas recently abandoned by glaciers.
grained material with thin organic
accumulations.
Outwash-train
Chiefly pebble and cobble gravel and
Smooth with gentle slopes except steep at terrace edges;
sand, well bedded and sorted.
accumulated mainly in front of end moraines, downstream
of meltwater-channel deposits.
Chiefly silty clay, silt, and fine sand,
Smooth with slopes nearly flat; locally marked by subdued
(Glacio) Estuarine
well bedded and sorted; locally includes
hills and irregularities; accumulated in ancestral Cook Inlet
thin beds of peat and other organic
marine environment, coarser facies deposited at glacier tide-
material; also locally includes diamic-
water margin.
ton, coarser sands, and gravels.
(Glacio) Lacustrine Interbedded clay, silt, and sand; well
Smooth with gentle slopes, but very steep at valleyward
to somewhat poorly sorted.
margins; accumulated in freshwater bodies (large lakes to
small ponds) ponded by glacier ice or moraine deposits.
A mound, ridge, or other accumulation of glacial sediment
Moraine
producing a variety of landforms.
End moraine
Juxtaposed sequences of deposits from
A gently arcing ridge or series of ridge segments deposited
polygenic origins, primarily diamicton
at the end (or terminus) of a glacier.
(poorly sorted admixtures of silt, sand,
and gravel) along with coarse gravel,
fine well-sorted sand, dense silt, and
clay, moderately to well compacted.
Lateral moraine
Sand, gravel, and diamictons.
A ridge or ridge segments deposited at the side margin of a
glacier. Commonly form gently sloping, sharp-crested ridges
along the walls of valleys that glaciers formerly occupied.
Ground moraine
Diamicton of variable thickness; may
Smooth to hummocky, with gentle to moderately gentle
contain thin, interbedded sand, silt,
slopes; deposits left behind when glaciers retreat.
and gravel horizons, and thin outwash
gravel or lake deposits on the surface.
Chiefly peat; includes organic-rich silt,
Smooth with very gentle slopes; accumulated in ponds or
Pond and bog
minor woody horizons, and thin
small former lakes or stream channels that filled with organic
interbeds of ash-sized tephra.
material.
Mainly angular to some subrounded
Moderately hummocky and rough, slopes moderate to very
Rock glacier
rock fragments being actively trans-
steep; mixture of rock fragments and ice-rich matrix is transi-
ported; contains ice-rich matrix; fines
tional between a true glacier and a slow-moving landslide.
from cobble- and boulder-size frag-
ments at surface to more rubbly dia-
micton character at depth.
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