Historical Geology

Nicholas Stenob. 1638, d. 1686Danish Geologist and StratigrapherDeveloped “Principle of Original

Horizontality”: All rock layers are flat unless otherwise disturbed.

Developed the Law of Superposition: That oldest layers are on the bottom and youngest layers are on top.

Developed “Cross-Cutting Relationships Principles”: States that if a body of rock cuts through another body of rock, the first body of rock must be younger.

James Huttonb. 1726, d. 1797Scottish naturalist and geologistConsidered the “father of modern

geology.”Uniformitarianism: The present is

the key to the past. Developed ideas of Geologic Time

and “Deep Time.” Further developed “Principles of

Cross-Cutting Relationships”Gradualism vs. Catastrophism

Charles Lyellb. 1797, d. 1875Wrote “Principles of Geology”Friend of Charles DarwinInspired by James HuttonSynthesized ideas from Steno,

Hutton, and Darwin. Solidified the Theory of

Uniformitarianism.

Charles Darwinb. 1809, d. 1882English NaturalistStudied Geology with Charles LyellHMS BeagleWrote: On the Origin of Species in which

he proposes the idea of evolution that results from natural selection.

Later accepted as the Theory of Evolution

Darwin’s ideas revolutionized geology and paleontology (study of fossils and past life).

Geologic Time (Deep Time)Deep Time: The idea that Earth

must be extremely old in order for geologic processes and evolution to occur.

Earth is now dated at 4.6 billion years old through radiometric dating of meteorites.

Geologic Timescale

In Groups, put these events in order from first (oldest) to last (most recent).

First FishesFirst Land PlantsFirst TreesFirst GrassesFirst ReptilesFirst AmphibiansFirst DinosaursFirst MammalsFirst PrimatesFirst BirdsFirst Flowering PlantsEvolution of Humans

Geologic ErasPaleozoic: Means “Ancient Life.”

◦ -Age of Fishes◦ -Cambrian Explosion (life evolved at an

alarming rate during this period)◦ -Ended with Permian-Triassic Extinction

Mesozoic: Means “Middle Life.”◦ -Age of Reptiles or Age of Dinosaurs◦ -Mammals appeared at this time.◦ -Ended with Cretaceous-Tertiary (K-T) Extinction

Cenozoic: Means “New Life.”◦ -Age of Mammals ◦ -Evolution of Humans

All of Earth’s History in 24 Hours