Catastrophism and Georges Cuvier

Study Notes

Catastrophism explains Earth's landscape as formed by abrupt, violent, short-lived, and possibly global events, leading to mass extinction and landscape changes.
Under catastrophism, mountain ranges form from sudden, massive uplifts caused by earthquakes.
This theory emerged when the scientific community needed to reconcile with the Bible's catastrophic narratives, like Noah's flood.
The astronomy community at the time largely viewed the universe as static.
Georges Cuvier, a French paleontologist in the early 19th century, popularized catastrophism, using fossil record observations.
Cuvier observed that fossils disappeared abruptly above certain geological strata, suggesting long periods of stability interrupted by catastrophes.
Cuvier's observations led him to believe that Earth is millions of years old.
Catastrophism was eventually replaced by uniformitarianism.

Uniformitarianism Evolution

James Hutton, a Scottish geologist considered the father of geology, proposed an alternative explanation for landscapes like sedimentary rock processes.
Charles Lyell expanded on Hutton's ideas, popularizing uniformitarianism (gradualism) in his 1830s book, Principles of Geology.
Lyell stated that current geological processes are key to understanding Earth's past.
Lyell rejected the idea that cataclysms could explain Earth's landscape, as such events don't occur on a large enough scale today.
Lyell argued that Earth's surface was shaped by long-term, gradual processes like earthquakes, volcanism, weathering, and erosion.
Geologists widely accepted uniformitarianism from the time of Principles of Geology until the late 1970s, due to observable processes.
The shift to uniformitarianism led scientists to believe Earth was much older than previously thought.
In 1956, Clair Patterson determined Earth's age to be about 4.5 billion years using uranium-lead dating.
Charles Lyell's Principles of Geology influenced evolutionary theories concerning the fossil record.
Lyell initially rejected long-term evolutionary theories but later accepted natural selection after reading Charles Darwin's works.

Uniformitarianism vs Catastrophism

Uniformitarianism contrasts with catastrophism.
Catastrophism posits a relatively stable geological history punctuated by intermittent cataclysms.
Uniformitarianism explains crustal changes through continuous, uniform processes like weathering, sedimentation, erosion, volcanism, earthquakes, and plate tectonics.
The popularity of uniformitarianism led scientists to distance themselves from religion and catastrophic theories.
It was difficult to be taken serious with any new theories or geological explanations connected to catastrophes during the early 1900s.
In 1923, J Harlen Bretz proposed that the channeled scablands in Washington State resulted from the glacial Lake Missoula bursting.
Bretz hypothesized that floods spanning 5,000 square kilometers occurred about 14,000 years ago.
The geological community initially rejected Bretz's explanation but later awarded him the Penrose Medal.
Bretz originally argued for one cataclysmic flood but later settled on multiple floods over a longer period, due to uniformitarianism.
Scientists still debate the number of floods.
The paradigm of uniformitarianism made it difficult for Luis and Walter Alvarez to support their asteroid impact hypothesis in 1980.
The asteroid impact hypothesis explained the Cretaceous-Paleogene extinction event 66 million years ago, leading to the extinction of the dinosaurs.
The Alvarez's supported their hypothesis with data collected at the k-t boundary layers of rock and strata from across the Earth.
Their hypothesis was initially met with scrutiny but was supported by the discovery of the 180-kilometer crater at the Yucatan Peninsula in 1990.

Modern Consensus

The works of geologists like J Harlen Bretz, and Luis and Walter Alvarez, shifted the paradigm theory of uniformitarianism in the late 20th century and early 21st century.
Geologists now accept cataclysms at a global scale, such as the collision that formed the Moon.
Earth's geological history is now viewed as primarily shaped by gradual processes (erosion, plate tectonics, volcanism), but interrupted by catastrophic events.
Sudden extinction events in the fossil record may be explained by asteroid impacts and supervolcano eruptions.
Some scientists suggest Earth's history has been influenced by coronal mass ejections and supernova gamma-ray bursts.
The Younger Dryas impact hypothesis suggests that fragments of a large asteroid impacted the Americas, Europe, and Asia around 12,800 years ago.
Supporting evidence includes shocked quartz, nanodiamonds, and high-temperature microspherules from the Younger Dryas boundary line.
This event may have caused the extinction of Pleistocene megafauna, the disappearance of the Clovis culture, and possibly a global flood and sea-level rise.
The hypothesis has faced scrutiny since its postulation in 2006.
The 30-kilometer crater under the Hiawatha Glacier in Greenland could provide credence to the hypothesis.