Founders%20of%20Historical%20Geology

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Founders of Historical Geology
Charles Darwin 1809-1882 Evolution organisms
changed through time Individuals with variations
most favorable in existing environment had best
chance of survival Passed these traits on to
next generation Natural Selection Also
recognized by Alfred Russell Wallace Neither
knew the mechanism, do you?
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Founders of Historical Geology
Charles Darwin 1809-1882 Origin of Species
1859 Documented two things 1. Evolution
occurred 2. Natural selection was
active how it worked Organic evolution became
the guiding principle of paleontological and
biological research
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Founders of Historical Geology
North American Notables William
McClure 1763-1840 Produced the first geologic
map of the US
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Founders of Historical Geology
North American Notables Amos Eaton 1776-1842 Tau
ght hands on geology at Rensselaer School
(RPI) Took long field trips Father of American
geology Studied New England region
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Founders of Historical Geology
North American Notables Louis Agassiz 1807-1873
Recognized that massive ice sheets once covered
North America First to hint at ice
ages Stated that glacial deposits did
not accumulate during Biblical flood
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Founders of Historical Geology
North American Notables James Hall 1807-1873 Fir
st director of NY State Geological Survey
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Founders of Historical Geology
North American Notables James D.
Dana 1813-1895 Published Manual of
Geology System of Mineralogy
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Founders of Historical Geology
North American Notables John Wesley
Powell 1834-1905 Director of USGS First to
traverse Grand Canyon by boat (1869) Union
officer in Civil War Lost arm at Shiloh
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Founders of Historical Geology
North American Notables Othniel C.
Marsh 1831-1899 Yale Edwin D. Cope 1850-1897 Penn
Both vertebrate paleontologists Exploited
fossil beds of western United States No
cooperation between two
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Founders of Historical Geology
North American Notables George Otis
Smith 1871-1944 Director of USGS 1907-1930 Colby
graduate, 1893
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Time and Geology
The fundamental interest in geology is to put
rocks in order time wise Geologists try to
establish a GEOCHRONOLOGY Steno, Hutton, Smith
etc tried by use of superposition, fossil
succession As science advanced we used
radiometric techniques.
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Time and Geology
Smith and contemporaries used RELATIVE GEOLOGIC
DATING techniques In relative dating, no
reference to actual time
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Time and Geology
ACTUAL OR NUMERICAL DATING tries to
assign numbers in terms of years to
events. Generally based on radiometric decay of
unstable elements Expresses actual age of
rocks or events
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Time and Geology
GEOLOGIC TIME SCALE
Subdivisions of Time Eons Eras Periods Epoc
hs
None last equal intervals of time. Based on
events.
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Time and Geology
Subdivisions of Time
EON Largest subdivision of Geologic Time
Scale Four Eons recognized Phanerozoic Protero
zoic Archean Hadean
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Time and Geology
Subdivisions of Time
Phanerozoic Eon 0.544 byBP present Includes
most sedimentary rocks and history of
life Proterozoic Eon 2.5-0.544 byBP Mostly
crystalline rocks Archean Eon 3.9-2.5
byBP Oldest preserved rocks Hadean Eon 4.63.9
billion years before present (byBP) No geologic
record
Precambrian
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Time and Geology
Subdivisions of Time
Phanerozoic Eon Three major subdivisions ERA C
enozoic Era (recent life) 65 myBP-present Mesozoi
c Era (middle life) 250-65 myBP Paleozoic Era
(ancient life) 544-250 myBP
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Time and Geology
Subdivisions of Time
Paleozoic Era 7 major subdivisions PERIODS Per
mian Pennsylvanian Mississippian Devonian Silurian
Ordovician Cambrian
Carboniferous
PALEOZOIC
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Time and Geology
Subdivisions of Time
EPOCH Periods are subdivided into EPOCHS Quatern
ary Period Holocene Epoch Pleistocene
Epoch Tertiary Period Pliocene Epoch Miocene
Epoch Oligocene Epoch Eocene Epoch Paleocene
Epoch
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Time and Geology
Subdivisions of Time
Units on the Geologic Time Scale represent actual
increments of time GEOCHRONOLOGIC UNITS Actual
rock units formed or deposited during these
intervals are CHRONOSTRATIGRAPHIC
UNITS Geochronologic Units Chronostratigraphic
Units Eon Eonathem Era
Erathem Period
System Epoch
Series Age
Stage
Chron Zone
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Time and Geology
Subdivisions of Time
Geochronologic units have the same names
as Chronostratigraphic units Jurassic
Period Jurassic System
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Time and Geology
Subdivisions of Time
Geologic Time Scale Organized using fossil
succession, superposition Then the units could
be correlated Resolution of Geologic Time Scale
still taking place today