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

34.2 (0.3) Stop at Garlock Road.
Look for oncoming traffic. TURN
LEFT (west) onto Garlock Road.
The trace of the Garlock fault is to
our right (Fig. 1-2). The first mining
for lode gold, silver, and copper
ore in the El Paso Mountains was
in 1863 on Laurel Mountain, east of
the El Paso Peaks.
John Goller, survivor of the 1849
Death Valley party, found gold nuggets
on his trek across the desert.
Although he regularly searched
for his lost “mine” placer gold was
not rediscovered here until 1893.
Miners named one of the prospects,
Goler Gulch, after Goller. By 1896,
a half-million dollars of gold had
been recovered (Vredenburgh,
2009; Vredenburgh and others,
1981).
35.4 (1.2) Continue past Goler Road on the left.
The Goler Formation lies to the north, in the northcentral
portion of the El Paso Mountains. The Goler
Formation consists of a two mile (3 km) thick section
of fluvial sediments capped by fossiliferous marine
sediments (Lofgren and McKenna, 2002; Cox and
Edwards, 1984; Cox and Diggles, 1986; McDougall,
1987). Intense prospecting for fossils by the “Goler
Club” has collected a suite of small mammals that
represent four NALMA that span the Paleocene (Lofgren,
et al., this volume). This is the best section west
of Wyoming and Colorado for studying Paleocene
faunas (60 Ma). No fossils have been recovered from
the lower members (1 & 2) of the Goler Formation,
but if rates of deposition can be considered constant,
lower strata project as Cretaceous in age (Cox, 1998).
Clasts in the Goler Formation tell us that the Mojave
Block to the south was elevated in the early Tertiary
(Cox, 1998). Prepare for a right turn on Charley
Road.
38.0 (2.6) TURN RIGHT on Charley Road. Proceed
north 0.2 mile.
38.2 (0.2) PARK along the road and WALK NORTH
to the fault scarp.
STOP 1-1 (N 35°25’26.2”; W 117°44’15.5”). Cabins
at the base of this 25–30 foot high scarp (Fig. 1-3) are
owned by the BLM as part of their Adopt-A-Cabin
program.
D. R. Jessey and R. E. Reynolds
Figure 1-3. Charley Road (Stop 1-1) View east along Garlock Fault, the skyline notch above
road, and playa-filled graben on north side of fault scarp. [J. Westbrook photo]
To the north from this escarpment is the southern
flank of the El Paso Mountains. The rocks making up
this portion of the El Paso Mountains are generally
undifferentiated Paleozoic roof pendants and Mesozoic
granitoids. The east–west striking El Paso fault
(south side down) lies at the base of the slope and
the 160 mile long Garlock fault along the base of this
north-facing scarp (Fig.1-2). Look southeast across
Cantil Valley to old alluvial ridges that mark the trace
of the Cantil Valley fault that parallels the Garlock
fault on the south side of Koehn Lake.
The Garlock fault zone marks the geologic province
boundary between the Mojave Desert to the south
and the Sierra Nevada and Basin and Range to the
north. Movement along the Garlock fault is thought
to have begun at about 10 Ma (Burbank and Whistler,
1987). While no surface rupture has occurred on
the Garlock fault in historic times, there have been
a few sizable quakes. The most recent was a magnitude
5.7 near the town of Mojave on July 11, 1992
(SCEDC earthquake database). It is thought to have
been triggered by the Landers earthquake, two weeks
earlier (Jones, Mori and Hauksson, 1995). Trenching
suggests other ruptures occurred in 1050 A.D. near
Tehachapi and 1500 A.D. near our present location.
At least one section of the fault has shown movement
by creep in recent years. Numerous studies have been
published citing slip rates along the fault (LaViolette,
et. al., 1980; Clark and Lujoie, 1974; Carter, 1980,
1982; Smith, 1975; McGill and Sieh, 1993; Petersen
10 2009 Desert Symposium