R.
Lopez
Read
about sedimentary rocks in Harden, p. 26-31, p. 36-37 and see Table 2-3.
1)
What
are the three reasons that sedimentary rocks are particularly important?
2)
Be
able to briefly discuss the four main processes involved in turning parental
solid rock into sediments and eventually sedimentary rock.
3)
What
are the two kinds of weathering and give an example of each?
4)
Give
three examples of agents that transport sediments.
5)
Be
able to name at least three non-marine and three marine depositional
environments.
6)
What
is a sedimentary “fan”, and what does alluvium mean?
7)
Lithification
involves commonly involves three steps, what are they?
8)
What
are the two major groups of sedimentary rocks (see text, Table 2-3)?
9)
What
does “clastic” mean?
10)
Define
the following: conglomerate, breccia, sandstone, shale, and mudstone.
11)
What
does the term “fissile” mean? And what rock does it best describe?
12)
What
are the two subdivisions of the Biological/Chemical group (also known as the
Chemical Precipitate group)?
13)
Define
Limestone.
14)
Cite
three examples of marine organisms that extract calcium carbonate from
seawater, and whose skeletons may form limestone. Is most limestone of inorganic or biological origin? What is calcareous ooze?
15)
What
are radiolaria (see Harden, fig. 3-10)?
What are their shells mad of? What are the deposits of radiolaria on the
seafloor known as?, and what kind of rock do they eventually form?
16)
Chert
is composed of what mineral?
17)
What
are diatoms and what are their deposits called (read Harden, p.441, and note
pictures on pp. 442-443)?
18)
What
famous geological formation in California is a Diatomite?
19)
What
principle do geologists use to interpret ancient depositional environments?
20)
What
kinds of features in sedimentary rocks provide information on depositional
environments?
21)
What
is compositional maturity?
22)
What
is textural maturity?
23)
What
tectonic setting are quartz sandstones, arkose sandstones, and greywacke
sandstones deposited in?
24)
Where
is clay size sediment most likely to be deposited in the marine environment?
25)
In
a bedded sequence of sedimentary rocks, what does each bed represent in terms
of depositional environments?
26)
What
are cross beds and how do they form?
27)
What
are graded beds and how do they form? What is a Turbidite?
28)
What
is the CCD? What is the reaction
involved to form carbonic acid?
29)
Be
able to sketch a “trailing continental margin” showing the continental shelf,
slope, rise, and deep ocean (abyssal plain).
Where would you expect reefs, turbidites, and oozes to be deposited?
Scenic Places to Visit to
See Interesting Sedimentary Rocks:
Pigeon Point Lighthouse on Highway 1 between Santa
Cruz and Half Moon Bay. Conglomerates
containing boulders and cobbles of volcanic rocks, granites, and fine sandstone
are exposed along the beach north of the lighthouse. Submarine landslides probably deposited these sediments.
Devil’s Slide on Highway 1 between Half
Moon Bay and Pacifica. It is too
dangerous to stop you car here, but beautiful turbidites are exposed in the
road cuts. To the north San Pedro Rock
can be seen in close to shore, and on a clear day the Farallon Islands can be
seen far offshore. The turbidites
exposed at Devil’s Slide also crop out near San Pedro Rock, and you can safely
examine them there.
San Pedro Rock. Take the southern most exit in Pacifica, head towards the ocean,
and ask someone how to get to Shelter Cove.
The latter is a small community on the beach, but the road to it was
lost to landslides years ago and now you must walk in. Great views of the Rock, and good exposures
of turbidites. Look for graded
bedding. The Rock is a hogback (see
below).
Vasquez Rocks. Off the Antelope Valley Freeway (Highway 14) between Los Angeles
and Palmdale. Exit at Agua Dulce Canyon
and follow the signs to the County Park.
The landform here is a “hogback ridge” (a ridge formed by resistant
layers within steeply tilted eroded strata) formed by erosion of resistant
sandstone and fanglomerate layers (a special name for conglomerates found in
alluvial fans).
Mormon Rocks. See Harden plate 28. These sandstone hogbacks have caught your eye if you have driven on Highway 138 between Palmdale and San Bernardino.
Pt. Lobos State Reserve. The “Crown Jewel of the California State Park System”. Located a few miles south of Carmel on
Highway 1. Only about an hour and a
half drive from San Jose. Beautiful
conglomerates and sandstones with interesting sedimentary structures, all
unconformably lying on Mesozoic Granite of the Salinian Block.