Chester Creek. Erosion in this channel was
breakout process probably occurred repeatedly,
less deep than in major channel and was
resulting in a complex of deposits. Although
not followed by significant deposition of
commonly referred to as "Naptowne outwash,"
these deposits are not outwash in the strict sense.
gravel and sand. Instead, deposits are
Contacts are well defined. Topography is smooth,
finer-grained or more poorly sorted and
with slopes being gentle to very gentle.
numerous boulders are present on ground
surface. May represent lag concentrate
mvf Mountain View alluvial-fan deposits--
from erosion of earlier glacioestuarine or
mvfu Chiefly cobble gravel near apex of fan;
moraine deposits, or both, or may have
grade southwestward to finer grained
formed as debris flow developed during
gravel and sand; mainly sand at distal end
rapid erosion of those deposits. Peat depos-
west of map area. Thickness 10 m or more.
its may have accumulated at surface in
Occur in broad, low-gradient alluvial fan
places, but most of these have been
that heads at south edge of the broad Eagle
removed during urbanization. nccu are
River Valley where it emerges from the
deposits further modified by urbaniza-
Chugach Mountains and that extends
tion.
southwestward to downtown Anchorage.
Named from community of Mountain
Alluvial deposits of local mountain-valley source.
View at west edge of map area. Complex
These are chiefly gravel and sand, well bedded
nature of fan indicated by presence of sev-
and well sorted. Contacts are well defined except
eral levels near head of fan separated by
as noted. They occur mainly in large alluvial fans,
small scarps, although these levels have
in terrace remnants at higher levels, and in chan-
not been correlated directly with two
nels that are cut below the level of fans or extend
higher-level remnants mapped farther
from them. They formed both before and after the
down the fan, mainly south of Ship Creek.
incursion of the Eagle River; some high-level
In that vicinity the fan has been dissected
deposits probably correlate with outwash from
by ancestral Ship Creek and subsequent
Elmendorf glacier.
deposition has partly filled some of the
The Ship Creek deposits are subdivided into
resulting channels. mvfu are deposits mod-
deposits at six levels: three cut below level of
ified by urbanization or other anthropo-
Mountain View fan in two different channels, one
genic activity.
at about fan level, and two at levels higher than
mvi Deposits at intermediate level--Occur in a
that of the Mountain View fan farther up Ship
remnant slightly higher than main part of
Creek near the Chugach Mountain Front. Thick-
fan; extend southwestward from south of
ness is probably several to 10 m.
Ship Creek to south of Glenn Highway.
mvh Deposits at highest level--Occur in rem-
scl
Lower-level deposits (Holocene)--Extend
mvhu nants substantially higher than main fan;
sclu
along present course of Ship Creek from
extend discontinuously from north of Ship
Chugach Mountain Front nearly to its
Creek to Middle Fork Chester Creek. mvhu
mouth, mainly in extensive low terrace
are deposits modified by urbanization.
that gradually becomes higher to the west.
nc
Nunaka Valley channel deposits--Thick-
sclu are deposits modified by urbaniza-
ncu ness at least 10 m. Occupy major channel
tion.
that lies at higher altitude than, and to the
scc
Chester Creek deposits (early Holocene?
and late Pleistocene)--Occur in channel
southeast of, Mountain View fan. Extend
sccu
developed by ancestral Ship Creek when it
from Ship Creek to South Fork Chester
flowed southwestward from its present
Creek. Probably represent earlier episode
of drainage from glacial Lake Eagle; alter-
northernmost reach and formed channel
natively, could be derived largely from
now occupied by lower course of Chester
Ship Creek. ncu are deposits modified by
Creek. sccu are deposits modified by ur-
urbanization.
banization.
ncc
Checkmate boulder-rich deposits--Occur
sch
Chester Creek deposits at higher level
nccu in smaller channel that branches off major
schu
(late Pleistocene)--Occur mainly in broad
channel and lies southeast of it and that is
schp
channel cut slightly below level of Moun-
now occupied by underfit South Fork
schpu
tain View fan when ancestral Ship Creek
56
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