Landscape Evolution at an Active Plate Margin - Biological Science ...

aine deposits. The Convict Lake basin lies between
the two mountain masses. The basin is an excellent
example of a U-shaped glacial valley.
As is the case with many glacial deposits throughout
the Sierras, there has been significant disagreement
as to the ages of the Convict Creek moraines. Blackwelder
was the first to study and interpret age relationships
of these deposits when he visited the area
in the 1920s. Subsequently, others have examined the
Convict Creek moraines with a variety of interpretations
as to their age relationships (see Lipshie, 2001
for a discussion of these interpretations). RETRACE
to Hwy 395.
73.6 (0.1) TURN LEFT (north) on 395.
75.0 (1.4) TURN RIGHT on Hot Creek/Fish Hatchery
Road, the paved road to Hot Creek.
75.2 (0.2) Pass a right turn to Mammoth/June Lake
airport (Airport Road).
75.5 (0.3) TURN RIGHT on Hot Creek Hatchery
Road.
75.9 (0.4) Pass the fish hatchery,
where they use heated water from
Hot Creek to raise the fish. The Hot
Creek Fish Hatchery is down the
gravel road to the left. While not
the most geologic of stops, children
really love it! Near the hatchery,
geothermal springs mix with the
water from Hot Creek. The result
is a series of ponds that maintain
year-round temperature of 55 to
63°F, an ideal environment for incubating
trout eggs and raising fish.
The hatchery, run by the California
Department of Fish and Game, has
been in operation since the early
1930s. Children love to feed the
fish (costs a quarter), but stick your
hand in the water at your own risk!
76.1 (0.2) We are driving over a late
D. R. Jessey and R. E. Reynolds
Table 2-3. Glacial Sequences of the Eastern Sierra Nevada
North American
(modified from Lipshie, 2001)
Blackwelder Sharp and Birman Lipshie (2001) Absolute Age
Sequence
(1931)
(1963)
(years B.P.)
Matthes
0-700
Post-Wisconsin
Recess Peak
2000-4000
Late Wisconsin
Early Wisconsin
Illinoian
Kansan
Nebraskan
Tioga
Tahoe
-
Sherwin
McGee
Tioga
Tenaya - Tahoe
Mono Basin
Sherwin
McGee
Hilgard
Tioga
Tenaya- Tahoe
Mono Basin
Sherwin
McGee
9000-10,500
12,000-25,000
45,000-75,000
About 130,000
About 800,000
1,500,000-2,500,000
Quaternary fault scarp that had minor
additional offset in 1980. This linear,
low scarp cutting late Pleistocene basalt
is one of several pre-existing faults that
ruptured at the surface during the 1980
earthquake swarm; this one possibly is a
splay of the Hilton Creek fault. Extension
cracks appeared on Hot Creek
Road trending in a northwest–southeast
direction at the base of the southwest-facing fault
scarp. Extension varied from 0.5 to 3 inches, with individual
cracks reaching 15 to 20 feet in length. Vertical
displacement ranged from 6 inches to about one
foot. Field mapping and fault plane solutions suggest
extension, but the actual displacement mechanism is
complex, possibly involving magma movement.
76.7 (0.6) Road bears left at T-intersection and pavement
ends.
78.2 (1.5) TURN LEFT into the Hot Creek Geologic
Site parking area and PARK.
STOP 2-6. Hot Creek (37°39’38”N, 118°49’40”W).
From the interpretive overlook, note the steam rising
from fumaroles and hot springs along the creek (Fig.
2-7). Hot springs also discharge directly into Hot
Creek near the remains of the bridge that formerly
spanned the creek. The mingling of hot spring water
with snow-melt fed stream water produces extreme
temperature gradients in the creek. The wide range of
Figure 2-7. View looking to the west along Hot Creek. Light-colored areas have been
hydrothermally altered by geothermal waters. [Source: Farrar, Evans, Venezky, Hurwitz
and Oliver, 2007]
38 2009 Desert Symposium