Geologists | GEOL-1122

Georges Cuvier(1800s)

• Discerned that some animals that lived on earth no longer exist (extinction)

• Each new catastrophe caused selective extinctions and opportunities for special creation.

• Did not think there was a connection between fossils in successive strata

• Believed there was an evolutionary do-over after every mass extinction

Georges-Louis Leclerc, Comte de Buffon(1749)

• Influential proponent of evolution and deep time

• Defined species

• Environment molds species through adaptation & inheritance

• Diversity increases over time

• Acquired characterization(incorrect)

• Had a lot of skepticism against him due to mummified cats, the lack of a coherent mechanism, and contradictions in his book

Nicolaus Steno (1638-1686)

• Rocks preserve a chronological record of Earth’s history

• Recognized fossils formed together with rocks

• All sediments and layers of rock are not the same age

• Defined 3 basic principles of sedimentary rock record (Superposition, Original Horizontality, and Lateral Continuity)

James Hutton

• Anti catastrophism, very pro deep time

• Developed the concept of plutonism

• High temperatures and pressures within Earth cause intrusions in the crust.

• Discerned that Earth goes through cycles of deposition, upheaval, and erosion.

• Created precursor to the rock cycle, discerned that sedimentary rocks are made of other rocks

• Discerned that uncomformities are missing layers(time) between two layers(Jedburgh Site)

• “No vestige of a beginning, no prospect of an end”

• Processes are uniform through time

• Geologic processes are in one part destructive and another part constructive

Charles Lyell

• ‘s Uniformitarianism - uniformity of changes + uniformity in rate & intensity of changes

• No extinction, incompatible with evolutionism

• Earth has “seasons” (time circles?)

Jean-Baptiste Lamarck(1744-1829)

• Species could change through time

• Daily spontaneous generation

• Species climbed through “ladder of life”

• Inheritance of acquired characteristics (incorrect)

Charles Darwin

• Naturalist on the HMS Beagle (1831-1836) when he began formulating the theory of evolution

• Evidence for evolution included linear classification, homologous structures, vestigial structures, embryology, and biogeography

Sedgwick & Murchison

• Geologists whose friendship got broken up over classifying the “Ordovician” era.

• Defined 4 out of 12 periods in Phanerozoic Era.

• Cambrian, Silurian, Devonian, Permian

Arthur Holmes

• Incorrectly determined earth was 1.6 billion years old based on the age of minerals within a rock

• Created the first radiometric timescale

• Not everyone was convinced

William “Strata” Smith

• Surveyor who planned canal routes

• Saw repetition of stratigraphic sequences across England and discerned that fossils were unique to each stratum

• Published the first high quality geologic map by using correlation to establish age equivalence

• Created the criteria for index fossils

Charlotte Murchison

• Collected fossils, her findings contributed to research of major geologists such as Charles Lyell

• Produced precise field sketches and geological landscape drawings.

• Advanced women’s access to science by insisting on attending Charles Lyell’s geology lectures at King’s College London

A.G. Werner

• Famous neptunist that believed the earth’s crust was formed by the depositing of sediments from a prehistoric flood.

• Discerned that earth is older than humanity

Robert Hooke

• Discerned that fossils have an organic origin

• Fossils can be used to date rocks

• Species can go extinct

Clair C. Patterson

• Found Earth was 4.56 billion years old by radiometric dating a meteorite