Geology
of California Robert Lopez
1)
What
is the age of the Franciscan Formation and what is its tectonic environment.
2)
What
are the principle rocks of the Franciscan Formation? Name the marine rocks and
the ocean lithosphere rocks.
3)
Much
of the Franciscan is a “melange”; what is a melange (plate 4, Fig. 12-16)?
4)
Make
a simple three-part sketch (like the one we did in class) showing the
development of the San Andreas Transform (also see Harden, Fig. 12-2, p. 282).
5)
What
are the plates involved in the Mendocino triple junction?
6)
When
was the initial contact between the Pacific Plate (East Pacific Rise) and North
American Plate?
7)
Why
is the distinction between the San Andreas Transform and San Andreas Fault
important?
8)
What
is the Salinian Block?
9)
Compare
the Salinian Block basement rocks (Mesozoic granites, metamorphic roof
pendants) with those of the Franciscan Formation (subduction zone rocks).
10)
What
does the Salinian Block represent in terms of plate tectonics, where are its
boundaries, where did it originate, and how far has it traveled (read the
following notes from lecture)?
The Salinian Block is an area in the Coast Ranges underlain
by granitic and high-grade metamorphic rocks that is bound on the east by the
San Andreas Fault and on the west by the Sur-Nacimiento Fault zone. The basement of the Salinian Block, which
represents a CONTINENTAL MAGMATIC ARC, contrasts sharply with those of the
Franciscan Formation that lies both to the east and west. (Recall, the Franciscan Formation has
oceanic affinities – e.g. contains fragments of oceanic crust and not granites
are present. The rocks of the
Franciscan Formation were deposited in a trench at a convergent boundary,
subducted, and metamorphosed at HIGH PRESSURE and relative low
temperature.) Rocks of the Salinian
Block originated in the area of the present Mojave Desert region, between the
southern Sierra Nevada and the Peninsular Ranges batholiths, and they have been
displaced at least 315 km (180 mi) northward by movement on the San Andreas
Fault.
11)
What
kind of rock forms the Pinnacles in the Pinnacles National Monument?
12)
What
is the approximate age of the Pinnacles and Neenach volcanic fields, what is their
geographic relationship, and what evidence do they provide concerning movement
along the San Andreas fault?
On our field trip, we will see these prominent geographical features: Santa Lucia Range, Salinas Valley, Gabilan Range, Santa Cruz Mountains, and Loma Prieta.
On
the cover of your textbook, locate the following: Monterey Bay, Santa Lucia
Range, Salinas Valley, Gabilan Range, Santa Cruz Mountains, Ben Lomond
Mountain, Santa Clara Valley, and the Diablo Range.
Make
sure you read the attached excerpt from Steinbeck’s East of Eden. Relate Steinbeck’s description to the
mountains and valleys visible across Monterey Bay.
Marine Terraces (Harden, p. 415-418)
1) What are marine terraces?
2)
What
two factors interplay to form marine terraces?
3)
How
do periods of glacial maxima (glaciers advancing on continents) correspond with
sea level changes?
4)
What
was the elevation of sea level during the last glacial maximum (?
5)
How
high would sea level be if all the present glaciers melted?
6)
Sketch
a diagram of the following: modern wave cut platforms; marine terraces; modern
and ancient sea cliffs and shoreline angles; terrace deposits.
On
plate 29 of your textbook (color plates between page 64-65), be able to identify
the Santa Cruz Mudstone, the Santa Cruz Age marine terrace, and the terrace
deposits (Harden’s caption is in error in describing the SC mudstone as a
sandstone).