What’s so remarkable about Hutton’s
Ideas?
• Contrary to prevailing views of the time
• Based on observation – what he saw
• Hutton drew inferences from his
observations
• Inferences are hypotheses
• Hypotheses are testable
• This is an application of the scientific
method to study of the Earth
Founders of Historical Geology
William Smith
1769-1839
English surveyor and mining engineer
Created the first geologic map
Understood sequences of rock, applied soils,
lithology, and fossils
First to recognize that rocks could be
identified by their fossil assemblages
First to “correlate” rocks of the same age
but different lithology
Founders of Historical Geology
William Smith
1769-1839
Correlation led to Principle of Faunal Succession
If we know the position of each rock layer in a
sequence, we know their relative age.
Then, if we look a the fossils in the layers, we can
determine the relative ages of them.
This sequence will occur again and again in the
geologic record on a widespread geographic scale.
Can then be used to provide relative age of the rocks.
Smith determined that the life forms of each age in Earth history
were unique for given intervals
Fossils could then be used to determine the chronology of the
rocks
Smith saw it, knew it was right, but didn’t know WHY
Founders of Historical Geology
Georges Cuvier 1769-1832
Alexandre Brongniart 1770-1847
Cuvier was a vertebrate paleontologist (left)
Brongniart was a naturalist
Founders of Historical Geology
Georges Cuvier 1769-1832
Alexandre Brongniart 1770-1847
Also recognized the utility of fossils for correlation
Validated Smith’s findings
Found that groups of fossils were separated by
erosional surfaces (unconformities)
Believed that these changes in life forms on Earth
were caused by catastrophic events
(catastrophe, extinction, creation of new life)
Founders of Historical Geology
Georges Cuvier 1769-1832
Alexandre Brongniart 1770-1847
This was contrary to Hutton’s uniform, gradual
change on Earth over long periods of time.
Led to a new school of thought: Catastrophism
Scientists argued Catastrophism vs Uniformitarianism
Which is right?
Founders of Historical Geology
Georges Cuvier 1769-1832
Alexandre Brongniart 1770-1847
What caused the abrupt changes observed at
unconformities?
Ancestors are observed in underlying strata.
Uniformitarianism held sway.
Catastrophic events do happen
volcanism, earthquakes, climate change,
meteorite impacts
Founders of Historical Geology
Charles Lyell
1797-1875
Published Principles of Geology
(5 volumes - 1830)
First textbook on Geology
Founders of Historical Geology
Charles Lyell
1797-1875
Principles of Geology
First to explain and synthesize geologic
observations
Added two more rules for interpreting geology.
Founders of Historical Geology
Charles Lyell
1797-1875
Principle of Cross-Cutting Relationships
Founders of Historical Geology
Charles Lyell
1797-1875
Principle of Inclusions
A
B
C
D
Aqueous
Volcanic
Metamorphic
Plutonic
Founders of Historical Geology
Charles Lyell
1797-1875
Andrew Ramsey stated:
“We collect the data and Lyell teaches
us the meaning of them”.
Founders of Historical Geology
Charles Darwin 1809-1882
Added to the understanding of Fossil Succession
Founders of Historical Geology
Charles Darwin 1809-1882
Clarified why the general
progression of fossils
worked
Evolution - organisms changed
through time
Provided the mechanism
for Fossil Succession