TM 5-852-2/AFR 88-19, Vol. 2
(b) Landform overlay and engineering mate-
--TL (thaw lakes), which indicate thermally
rials delineation. The original scale of the photos
unstable materials developing into a lake-studded,
used to create the stereoscopic photomosaic in
low-lying planar surface.
figure 3-5 is 1:62,500, or 1 inch to the mile. At this
--SD/AT (sand dunes lying upon an alluvial
scale, terrain information can be identified and
terrace), which are unfrozen sand dune deposits
delineated stereoscopically. However, reducing the
lying on a partially frozen alluvial terrace.
40- by 60-inch photomosaic and overlays to fit the
--CP (coalesced palsas), which are small
format of this publication has caused very fine detail
hillocks on a planar surface caused by local upheaval
to be eliminated. The mapped features in this
of the active layer in a permafrost environment with
example include the following:
fine, silty soils.
(c) Permafrost overlay. This overlay delin-
--MT (mountainous terrain), which occurs at
high elevations, and has a thin soil mantle, with bare
eates the permafrost-influenced terrain patterns from
rock outcrops.
the non-permafrost areas. The overlay is more or
--HT (hilly terrain), which occupies areas
less self-explanatory. This overlay, coupled with the
flanking high elevations as ridges or spurs. "Horse
tail" drainage can be associated with much of this
the alluvial deposits along the major river valley and
pattern, which is suggestive of ice-rich silty mate-
the sand-dune-covered terrace inside the broad bend
rials.
of the river as being the most promising areas to
--AF (alluvial fans), which are large, valley
investigate on the ground for site selection
fill, coalescing fan deposits. Long slopes, flat gradi-
purposes.
(d) Vegetation type and distribution over- lay.
ents and "soft"-appearing dissection by surface
drainage are indicative of ice-rich silty soils.
From the scale of photography used in this example,
--SS (solifluction slopes), which are slopes
no definitive identification of vegetation could be
flanking many of the mountains and larger hill
done. Special overflights to obtain imagery at scales
masses composed of unconsolidated deposits, satu-
larger than 1:10,000 would be required to evaluate
rated with water released by thawing.
the biological patterns of the landscape.
(e) Detailed permafrost features overlay.
--TK (thermokarst), which occurs here in
large, flat, ice-rich areas beyond the terminus of
Likewise, even to observe the numerous patterns of
valley fill alluvial fans.
permafrost (polygons, solifluction lobes, soil stripes,
--FP/F (flood-plain/fine-grained deposits),
frost boils, etc.), much larger scales of photography
which are ice-rich, silty deposits.
have to be used. Only the gross effects of
--FP/C (flood-plain/coarse-grained deposits),
permafrost were observed and used in creating a
which are predominantly unfrozen, alluvial sands
general permafrost overlay for this example
and gravels.
illustration.
3-14
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