Exam 3 Flashcards
When did dinosaurs become extinct
66 million years ago
What is the law of uniformitarianism
The present is the key to the past
the theory that changes in the earth’s crust during geological history have resulted from the action of continuous and uniform processes.
which is the longest period of time
precambrian
All geologic periods of time
- Cenozoic:
1. Quatemary
2. Tertiary - Mesozoic
1. Cretaceous
2. Jurassic
3. Triassic - Paleozoic
1. Permian
2. Carboniferous (1.
Pennsylvanian 2.
Mississippian)3. Devonian 4. Silurian 5. Ordovician 6. Cambrian
which era was the age of the dinosaurs?
Mesozoic
which is the current geologic era?
Cenozoic
Which isotope do we use to date events that occurred in the past 50,000 years?
carbon
if we have one quarter of the radio-active isotope parent left, how many half lives have passed?
2
what is the name of the radioactive decayed product?
the daughter
how old is the earth?
4.5 billion years
who is the father of geology
James Hutton
unconformity?
gaps in the geologic rock record. They are surfaces of contact between older rocks and younger sedimentary rocks, formed due to erosion or lack of sediment deposition over extended periods of time.
what is the principal of faunal succession?
based on the observation that sedimentary rock strata contain fossilized flora and fauna, and that these fossils succeed each other vertically in a specific, reliable order that can be identified over wide horizontal distances.
which radioactive method is used to date organic remains?
radio-carbon, the carbon nitrogen
What is the definition of half life?
The time required for one-half of the radioactive (parent) isotopes in a sample to decay to radiogenic (daughter) isotopes.
The time it takes mothers to make daughters
if you start out with 1,000 radioactive isotopes, after 2 half lives how many do you have left?
250
what was the highest form of life in the precambrian era?
bacteria
what forms of life existed in the precambrian era?
bacteria
what is the name of the Mesozoic supercontinent?
Pangea
approximately how many large lithospheric plates do we have?
12
how old are the oldest oceanic basalts?
200 million years
what type of a plate boundary is the san Andreas fault
transform
In what kind of a plate boundary do we find submarine trenches and volcanic island arcs
collision, or a convergent
which continents are a part of Gondwanaland?
Africa, south america, Antarctica, Australia, subcontinent of india. All southern continents.
what did vine and matthews explain about seafloor spreading?
they discovered the magnetic anomalies on the ocean floor. (magnetic stripes or magnetic reversals)
what is the orientation of the magnetic stripes on the ocean floor? which way do they go?
Parallel to the ridge, mirror image
how did the andes mountains form?
Collision of 2 lithospheric plates
what causes plate tectonics?
thermal convection generated by heat
what is Iceland part of?
its part of the mid-atlantic ridge
what was the name of the guy that originated Pangea?
alfred wegener
what kind of evidence did he use to prove pangea?
fossils, glacial deposits, rock formations, geographic fit
why was his theory rejected?
they did not have the right mechanism
below what temperature do you have to cool the iron rich basaltic to magnetize it?
the magma curie point (500 degrees celsius)
where would you find the youngest ocean floor basalts in the ocean?
by the ridge. they get progressively older the further away from the ridge you go
what kind of a boundary is the Himalayas?
conversion, collusion, compression
what is the definition oftransform boundary?
plates sliding past each other laterally
what is the definition of lithosphere?
the upper most regent part of the mantle and crust.
are volcanoes distributed evenly everywhere or do they occur along plate bound boundaries?
volcanoes are located along plate boundaries
