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EOSC 210 Questions with Detailed
Verified Answers
Question: Principle of original horizontality
Ans: -due to gravity, sedimentary rocks are deposited as horizontal layers
-folds, faults would have occurred after deposition
Question: Principle of Superposition
Ans: -in a sequence of bedded rock, the rock layer above is younger than
the ones below it
Question: Cross-cutting relationships
Ans: -igneous intrusions and faults are younger than the rocks that they
intrude or break
-states that any rock that cuts across or penetrates a second rock body is
younger than the rock it penetrates
Question: Principle of Lateral Continuity
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Ans: -rock units with similar characteristics can be correlated across
different exposures over large distances
-correlation can be aided using fossil assemblages, especially when
considering rock exposures separated by 10's to 1000's of km
Question: Unconformaties
Ans: -represent breaks in the geologic record (ie. erosional surfaces and
missing rock in the expected sequence)
-the surface separating two rock sequences
Question: Principle of Biotic Succession
Ans: -organisms have evolved and gone extinct through time, specific
groups of fossils succeed one another in the rock record in a definite order
(ie. evolution)
-fossil content can be used to help determine the age of the rock units
they're found in
Question: Relative dating
Ans: based on fossil assemblages
Question: Absolute dating
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Ans: e.g. radiometric dating
Question: Relative time
Ans: Age of units relative to one another 1. observed contact relationships
between rock units 2. fossil record
Question: Absolute time
Ans: specific age of a unit in years 1. Ga Giga annum (billion years ago) 2.
MA Mega annum (million years ago) 3. Ka Kilo annum (thousand years ago)
Question: Hadean Eon (4.0-4.5 Ga)
Ans: earths cooling period; widespread volcanism
Question: Archean Eon (2.5-4.0 Ga)
Ans: first unicellular life forms "age of bacteria"; oldest rocks found on the
planet; final stages of Earth cooling and formation of the crust
Question: Proterozoic Eon (2.5 Ga-545 Ma)
Ans: most diamonds formed; oldest sedimentary rocks; formation of
ozone layer; first multicellular organisms (jellyfish)
Question: Phanerozoic Eon (<545 Ma "visible life")
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Ans: Paleozoic Era: age of marine life; Mesozoic Era: reptiles; Cenozoic
Era: Mammals
Question: Three principles of geology
Ans: 1) Principle of original horizontality 2) Principle of original continuity
3) Principle of superposition
Question: Principle of Uniformitarianism
Ans: geological processes causing change on the earth are gradual rather
than catastrophic and are the same processes that can be observed today
Question: Compressional (P) waves
Ans: travel through both solids and liquids
Question: Shear (S) waves
Ans: only travel through solids
Question: Mantle
Ans: -viscous behavior
-consist of magnesium, iron and silicon
- ~300 km thick
EOSC 210 Questions with Detailed
Verified Answers
Question: Principle of original horizontality
Ans: -due to gravity, sedimentary rocks are deposited as horizontal layers
-folds, faults would have occurred after deposition
Question: Principle of Superposition
Ans: -in a sequence of bedded rock, the rock layer above is younger than
the ones below it
Question: Cross-cutting relationships
Ans: -igneous intrusions and faults are younger than the rocks that they
intrude or break
-states that any rock that cuts across or penetrates a second rock body is
younger than the rock it penetrates
Question: Principle of Lateral Continuity
, Page | 2
Ans: -rock units with similar characteristics can be correlated across
different exposures over large distances
-correlation can be aided using fossil assemblages, especially when
considering rock exposures separated by 10's to 1000's of km
Question: Unconformaties
Ans: -represent breaks in the geologic record (ie. erosional surfaces and
missing rock in the expected sequence)
-the surface separating two rock sequences
Question: Principle of Biotic Succession
Ans: -organisms have evolved and gone extinct through time, specific
groups of fossils succeed one another in the rock record in a definite order
(ie. evolution)
-fossil content can be used to help determine the age of the rock units
they're found in
Question: Relative dating
Ans: based on fossil assemblages
Question: Absolute dating
, Page | 3
Ans: e.g. radiometric dating
Question: Relative time
Ans: Age of units relative to one another 1. observed contact relationships
between rock units 2. fossil record
Question: Absolute time
Ans: specific age of a unit in years 1. Ga Giga annum (billion years ago) 2.
MA Mega annum (million years ago) 3. Ka Kilo annum (thousand years ago)
Question: Hadean Eon (4.0-4.5 Ga)
Ans: earths cooling period; widespread volcanism
Question: Archean Eon (2.5-4.0 Ga)
Ans: first unicellular life forms "age of bacteria"; oldest rocks found on the
planet; final stages of Earth cooling and formation of the crust
Question: Proterozoic Eon (2.5 Ga-545 Ma)
Ans: most diamonds formed; oldest sedimentary rocks; formation of
ozone layer; first multicellular organisms (jellyfish)
Question: Phanerozoic Eon (<545 Ma "visible life")
, Page | 4
Ans: Paleozoic Era: age of marine life; Mesozoic Era: reptiles; Cenozoic
Era: Mammals
Question: Three principles of geology
Ans: 1) Principle of original horizontality 2) Principle of original continuity
3) Principle of superposition
Question: Principle of Uniformitarianism
Ans: geological processes causing change on the earth are gradual rather
than catastrophic and are the same processes that can be observed today
Question: Compressional (P) waves
Ans: travel through both solids and liquids
Question: Shear (S) waves
Ans: only travel through solids
Question: Mantle
Ans: -viscous behavior
-consist of magnesium, iron and silicon
- ~300 km thick
