pf
Deposits in Fire Creek Valley (Holocene)--
Deposits not exposed; genesis and charac-
Early View deposits--Dominantly silt and
ev
ter mainly inferential. Probably silt, clay,
evpf
silty clay, locally may include fine sand.
and fine sand; may include thin tephra
evu
Thickness probably a few to several
beds and peat near surface. Deposits alter-
meters. If glacioestuarine, equivalent to
natively could be either 1) estuarine, formed
part of Bootlegger Cove Formation. Con-
in a narrow inlet of Knik Arm, or 2) mainly
tacts generally well defined. Topography
fine-grained alluvium of Fire Creek. Thick-
smooth, slopes nearly flat. Occur in broad,
ness probably several to a few tens of
channel-like area now occupied by a
meters. Contacts gradational to fine-grained
north-flowing reach of South Fork Chester
alluvium of present Fire Creek. Poorly
Creek, commonly downslope from adja-
drained.
cent Muldoon Road deposits. evpf is an
p
area containing permafrost; evu are depos-
Pond and bog deposits (Holocene and
late Pleistocene)--Chiefly peat (mosses,
its modified by urbanization.
pu
ppfu sedges, and other organic material in vari-
evp Deposits with peat at surface--Peat about 1
ous stages of decomposition); include silt,
m thick in a few central areas that are appar-
organic-rich silt, minor woody horizons,
ently less well drained than surrounding
and a few thin interbeds of mainly ash-
areas.
Coarse-grained deposits--Probably con-
sized tephra. At depth also may include
evc
evcu tain higher proportion of sand (and per-
clay, marl, or fine to medium sand. Accu-
haps some gravel) than remainder of de-
mulated mainly in former small lakes or in
posits to which they are mainly marginal.
former stream channels that are now bogs.
Also mapped south of North Fork Little
Soft and moist. Thickness commonly as
Campbell Creek where finer-grained
much as 4 m, locally as much as 10 m; adja-
deposits are lacking and identity is based
cent mapped deposits extend beneath
mainly on geomorphic relationship to
these deposits. Contacts well defined, but
adjacent, higher-lying Muldoon Road
deposits may grade laterally to the similar
deposits; here, less likely to be of lacus-
but much thinner mantle that overlies
trine origin. evcu are deposits modified by
adjacent deposits. Surface smooth; slopes
urbanization.
less than 1%. Poorly drained. Widespread
br
occurrences within Elmendorf Moraine
Birch Road deposits--Fine sand and silt,
and on the floor of Eagle River Valley;
finely bedded and well sorted, especially
common locally in areas of lateral mo-
where typically developed south of map
raines and associated channels. Scattered
area; here may be coarser-grained or more
occurrences elsewhere in Anchorage Low-
poorly sorted, or both, and may include
land; most peat there, however, probably
sand, gravel, and diamicton, especially
did not begin accumulating in ponds, and is
near map unit fk. Topography fairly
mapped with underlying alluvial deposits
smooth to slightly hummocky, slopes gen-
in map units schp, evp, and wsp. pu is peat
tle. Occur principally in narrow belt that
partially or totally removed during urban-
widens southwestward from South Fork
ization; ppfu is an area that probably con-
Chester Creek and that lies between about
140 and 200 m in altitude. Possibly depos-
tained permafrost.
ited in a local glacier-dammed lake or in a
basin-wide glacial lake.
Glaciolacustrine or glacioestuarine deposits
(late Pleistocene)
Glacioestuarine deposits or moraine and
These deposits accumulated either 1) in lakes
kame deposits modified in a glacioestuarine
marginal to glacier ice or in narrow valleys mar-
environment (late Pleistocene)
ginal to former glaciers when the valleys were
These occur in relatively prominent hills in
blocked by moraine remnants or alluvial fans of
Anchorage Lowland south of Elmendorf Mo-
mountain-origin streams, 2) in the margins of
raine. Formed either as ground moraine and as-
glacioestuarine waters as they rose, following
sociated kames and subsequently modified by
withdrawal of glacier ice, or 3) in a high-level,
wave and tide action in a glacioestuarine envi-
basin-wide glacial lake of the type envisioned by
ronment, or by redeposition of glacial deposits
Karlstrom (1964).
60
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