ounders of Historical Geology s Darwin 1809-1882 ion – organisms changed through time duals with variations most favorable in exis nvironment had best chance of survival these traits on to next generation l Selection lso recognized by Alfred Russell Wallace r knew the mechanism, do you?
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Founders of Historical Geology Charles Darwin 1809-1882 Evolution – organisms changed through time Individuals with variations most favorable in existing.
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Founders of Historical Geology
Charles Darwin 1809-1882
Evolution – organisms changed through time
Individuals with variations most favorable in existingenvironment had best chance of survival
Passed these traits on to next generation
Natural SelectionAlso recognized by Alfred Russell Wallace
Neither knew the mechanism, do you?
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 theguiding principle of paleontological and biologicalresearch
Founders of Historical Geology
North American NotablesWilliam McClure 1763-1840
Produced the first geologic map of the US
Founders of Historical Geology
North American NotablesAmos Eaton 1776-1842
Taught “hands on” geology at Rensselaer School (RPI)Took long field tripsFather of American geologyStudied New England region
Founders of Historical Geology
North American NotablesLouis Agassiz 1807-1873
Recognized that massive ice sheetsonce covered North America
First to hint at “ice ages”Stated that glacial deposits did notaccumulate during Biblical flood
Founders of Historical Geology
North American NotablesJames Hall 1807-1873
First director of NY StateGeological Survey
Founders of Historical Geology
North American NotablesJames D. Dana 1813-1895
Published Manual of GeologySystem of Mineralogy
Founders of Historical Geology
North American NotablesJohn Wesley Powell 1834-1905
Director of USGSFirst to traverse Grand
Canyon by boat(1869)
Union officer in Civil WarLost arm at Shiloh
Founders of Historical Geology
North American NotablesOthniel C. Marsh 1831-1899 YaleEdwin D. Cope 1850-1897 Penn
Both vertebrate paleontologists Exploited fossil beds of western
United States No cooperation between two
Founders of Historical Geology
North American NotablesGeorge Otis Smith 1871-1944
Director of USGS 1907-1930Colby graduate, 1893
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 etctried by use of superposition, fossil succession
As science advanced we used radiometric techniques.
Time and GeologySmith and contemporaries used
RELATIVE GEOLOGIC DATING techniques
In relative dating, no reference to actual time
Time and Geology
ACTUAL OR NUMERICAL DATING tries to assignnumbers in terms of years to events.
Generally based on radiometric decay of unstable elements
Expresses actual age of rocks or events
Time and Geology
GEOLOGIC TIME SCALE
Subdivisions of Time
EonsEras
PeriodsEpochs
None last equal intervals oftime.
Based on events.
Time and Geology
Subdivisions of Time
EONLargest subdivision of Geologic Time Scale
Four Eons recognized
PhanerozoicProterozoicArcheanHadean
Precambrian
Time and Geology
Subdivisions of Time
Phanerozoic Eon0.544 byBP – presentIncludes most sedimentary rocks and
history of lifeProterozoic Eon
2.5-0.544 byBPMostly crystalline rocks
Archean Eon3.9-2.5 byBPOldest preserved rocks
Hadean Eon4.6–3.9 billion years before present (byBP) No geologic record