Earth Sciences 240A Lecture 4.
Uniformitarianism
vs. Catastrophism
“Is the development of all aspects of Earth the result of slow,
predictable processes or is it the result of sudden, chance events…or a mix?”
If Catastrophic:
No value to scientific study of
Earth processes
No natural evolution
Only literal interpretation of
Bible
Neptunism
(preceded Catastrophism)
Championed by: A.G.Werner (mineralogist;
charismatic; persuasive speaker)
All rocks (even granite, basalt)
precipitated from primeval seas
Conformed to story of biblical
floods
Abandoned because could not explain
obvious volcanoes
James Hutton
(‘father of modern geology’)
Scottish physician; amateur
geologist (Remember his unconformity study)
Founded basic work for
uniformitarianism (=‘gradualism’); “The present is the key to the past”
Recognized long time essential
1795: published “The Theory of the
Earth”
Baron George Cuvier
Brilliant scientist; ‘politically
connected’
Champion of catastrophism
All changes: series of sudden,
widespread catastrophes
New/old organisms could migrate but
never evolve
His diligently recorded case
studies contained best evidence for extinctions
Had a tough time explaining
skeleton of a mastodon!
Catastrophism Model
Earth initially molten
Six catastrophes made to correlate
with 6 days of creation; 7th was flood
Episodic large-scale disruptions
during cooling (decreased with time)
Volcanoes were ‘last gasp’ of
cooling interior
Dominant from late 18th to mid 19th
C
Charles Lyell
Embraced ideas of Hutton
1830: “Principles of Geology”
Promoted unlimited geologic time
Creation vs.
Evolution
Lyell: small changes of flora/fauna
result of ‘sequential creation’
Charles Darwin (friend of Lyell):
Lyell’s book
influenced his observations
H.M.H.S. Beagle
1844: 200-page essay on “Natural
Selection”
Lyell agreed he couldn’t explain
‘apparent’ evolution of plants/animals – but no theory of evolution could ever
be applied to humans.
Our Modern View
Pro-Uniformitarianism points
Pro-Catastrophism points
Compromise (sort of!)
Next Lecture: Begin PART
B: Space Objects and Impacts