Geology
of California Robert Lopez
1)
What
is the time interval and what is significant about the Pleistocene Epoch?
2)
What
is the definitive characteristic of glaciers?
3)
What
are continental glaciers and did California experience continental glaciation?
4)
What
are the two remaining continental glaciers today?
5)
What
were the names of the continental glaciers that existed in North America during
the Pleistocene Epoch?
6)
What
are Alpine glaciers and how do they differ from continental glaciers?
7)
What
are cirques, crevasses, and ice falls (e.g. Harden, Fig. 8-40)?
8)
Be
able to label the following large-scale glacial erosional landforms common to
the Sierra Nevada: Aretes, cirques, tarns, horns, cols, hanging valleys, roches
Moutennees, pater noster lakes, and U-shaped valleys.
9)
What
is till and what is a moraine?
10)
Be
able to identify the following small-scale features common in the Sierra
Nevada: “roche moutonnees”, grooves and striations, glacial polish (p. 205).
11)
Be
able to identify the following depositional landforms left by the retreating
glaciers and common in the Sierra Nevada: terminal, recessional, medial, and
lateral moraines.
12)
What
are glacial erratics (dropstones) and how do we know they were transported by
glaciers (p. 8-48)?
13)
What
are four possible causes of Pleistocene glaciation?
14)
What
are the three aspects of Milankovich Cycles (read info on Astronomical Cycles
in side-bar box The Earth’s Climatic Cycles” on page 204)? What is Precession of the Equinoxes? What is
Changes in Obliquity? What is
Eccentricity?
15)
What
is aphelion?
16)
What
Sierran Glaciation formed the most conspicuous moraines now seen in the Eastern
Sierra Nevada?
17)
Why
are glacial moraine deposits more conspicuous on the east side of the Sierra
than those on the west side?
The
Automobile Club of Southern California has a great map entitled Eastern Sierra
that covers Lone Pine to Bridgeport. If
you are a AAA member, you can pick up a copy at the AAA office in Bishop or
anywhere in southern California. This
map is detailed enough to show a lot of handy information. For example, the dirt road to Lookout
Mountain (the Resurgent Dome in Long Valley Caldera), which is the classic view
point of the Long Valley Caldera, San Joaquin Ridge, Mammoth Mtn., and the
Minarets and Ritter Range.
Large
lateral moraines extend away from the Sierran Front between Big Pine and
Bridgeport. You can drive up moraines
on Hwy. 168 from Bishop to Lake Sabrina and on the Glacier Lodge Road from Big
Pine. The trail head to the Palisade
Glaciers is near in near Glacier Lodge.
A round trip to the glaciers involves two days of strenuous hiking at
elevations up to 14,000 ft.
Know
that Yosemite Valley was a broad valley during the mid-Tertiary before uplift
and tilting of the Sierra Nevada that started about 5 to 10 m. y. ago.
As
a result of the uplift, the rate of erosion increased, and in the early Quaternary
before glaciation, the Valley moved into the “canyon stage” a V-shaped
valley. The lower elevation portion of
the Merced River west of Yosemite that was never glaciated is still V-shaped
and in the canyon stage.
During
the most intensive period of Pleistocene glaciation, glaciers reached near the
tops of Clouds Rest, Half Dome, and El Capitan, but did not override them. Glaciers plucked slabs of rocks off Half
Dome along joints, forming the steep cliff.
At
the end of Tioga glaciation, a terminal moraine stretched across the valley
from El Capitan to Bridal Vail falls.
This moraine formed a dam for Lake Yosemite, and about 2000 ft. of lake
sediments accumulated behind the dam.
Consequently, the floor of Yosemite Valley is much flatter than a typical
U-shaped glacial valleys.
Tunnel
View – Top view of the Valley according to PhotSecrets
of Yosemite. For even better views,
hike to Inspiration Point or Old Inspiration Point.
Sentinel
Dome – See the famous, twisted (and now dead) Jeffery Pine.
Glacier
Point – One of the most inspirational viewpoints in the world (you may not be
able to get to this view point because of recent rock slides along exfoliation
sheets).
Olmsted
Point – On Hwy. 120 to Tuolumne Meadows and Tioga Pass. Great and unusual views of Half Dome, Clouds
Rest, and Tenaya Lake. A good place to
see many glacial features and the Half Dome Granodiorite.
Toulumne
Meadows – Many glacial features and Lembert Dome.
Lee
Vining Canyoun – A few miles beyond Tioga Pass and out of the Park. Drive down this spectacular glaciated
canyon. At the east end you will be
driving between two enormous Tahoe age lateral moraines and finally through the
terminal moraine.
Yosemite Road Guide – Keyed to roadside
markers. A must.
Yosemite Trails – by Lew and Ginny
Clark. Great information on all the
trials in the Park.
Domes, Cliffs, and
Waterfalls
– by W.R. Jones. A brief summary on all
the trails in the Park.
PhotoSecrets of Yosemite by Andrew Hudson. If you want to take photos of classic views
in Yosemite, but only have limited time there, this book can be most
helpful. It contains a list of the “Top
Ten” sights of Yosemite Valley along with the best time of day to photograph them.