This assigment is for Tolmie State Park in Olympia Washington. Rock types in and
ID: 290143 • Letter: T
Question
This assigment is for Tolmie State Park in Olympia Washington.
Rock types in and around Tolmie State Park:
Formation Name
Rock type
(be as specific as you can) and brief description
Ages: Oldest to youngest
(Ma = million years ago)
Evc ( c )
Crescent Formation
56 Ma
Continental glacial drift, pre-fraser
2.6 Ma
Em(2m)
Marine sedimentary rocks
56 Ma
Alluvium
2.58 Ma
MOigb
Gabbro
23 Ma
Nearshore sedimentary rocks
36 Ma
Dip-slip
Normal fault
Continental glacial outwash, sand, fraser-age
2.6 Ma
continental glacial till, Fraser-age
2.6 Ma
1. List the sequence of geologic events that tell the complete geologic story (history), explaining how the rocks in your project area fit into the larger regional geologic story, i.e. present and past plate tectonic setting and major events.
a. Write this in paragraph form (with complete sentences). Explain how each rock unit listed in your table above formed as part of the sequence of geologic events that shaped your project area.
b. Explain any deformation events associated with the faults/folds in the area and how they fit into the sequence of events. If possible, relate these to plate tectonic activity at the time these structures formed.
c. Refer to your figures and tables to help illustrate/explain each point.
d. Cite the geologic map and any other sources you consult as references in the proper format and cite each by number in your answers after any specific information you drew from it.
Formation Name
Rock type
(be as specific as you can) and brief description
Ages: Oldest to youngest
(Ma = million years ago)
Evc ( c )
Crescent Formation
56 Ma
QgpContinental glacial drift, pre-fraser
2.6 Ma
Em(2m)
Marine sedimentary rocks
56 Ma
QaAlluvium
2.58 Ma
MOigb
Gabbro
23 Ma
En(sk)Nearshore sedimentary rocks
36 Ma
Dip-slip
Normal fault
QgosContinental glacial outwash, sand, fraser-age
2.6 Ma
Qgtcontinental glacial till, Fraser-age
2.6 Ma
Tolmie State Park geologic map Legend Octk Octk) igt Tolmie State Park Qetk Qgt Qc(k) wtr Qgp wtr Qgd wtr Qa wtr wtr Qa Qgt wtr wtr wtr wtr Qgt Ev(c) Qgt gt Ev(c) 3 miExplanation / Answer
1.a. There are different era like Paleozoic , Mesozoic , Cenozoic. The data listed here is of Cenozoic era where - few of them are part of quaternary where rocks formed isnt old enough like in northern glaciers or alluvium etc. Some of the rocks are quite old in sedimentary rocks category.
During plate movements there are several folds and faults that occur around a certain period of time and younger rocks are thus exposed while older rocks remain subdued.
Presently in the areas of Washington the rocks is subjected to several erosin and weathering over a longer period of time.
b. The rocks listed in the table are a part of different era in which they were formed. Some were in the quaternary period of Cenozoic era or some were of tertiary period of the same.
The older rocks which got subdued because of plate tectonic movements while younger rocks formed the surface
Here Gabbro , Marine Rocks, and sedimentary rocks of seashore are of the tertiary period of cenezoic era in the geologic time scale as they were formed several MA.
c. Crescent Formation - It is a geologic formation in the areas of washington . It actually preserves fossils of the paleozoic period.
Fraser - Periodic changes in the earth's temperature have created changes in sea levels which have helped to form the island.
Sedimentary Rocks -
Sedimentary rocks are types of rock that are formed by the deposition and subsequent cementation of that material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral or organic particles (detritus) to settle in place. The particles that form a sedimentary rock by accumulating are called sediment.
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