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Denudation rates are usually much lower than the rates of uplift and average orogeny rates can be eight times the maximum average denudation. [24] The only areas at which there could be equal rates of denudation and uplift are active plate margins with an extended period of continuous deformation. [25] Denudation is measured in catchment-scale ...
Mass movement is the downward and outward movement of rock and sediments on a sloped surface, mainly due to the force of gravity. [28] [29] Mass movement is an important part of the erosional process, and is often the first stage in the breakdown and transport of weathered materials in mountainous areas. [30]
Exhumation by tectonic processes refers to any geological mechanism that brings rocks from deeper crustal levels to shallower crustal levels. While erosion or denudation is fundamental in eventually exposing these deeper rocks at the Earth's surface, the geological phenomenon that drive the rocks to shallower crust are still considered exhumation processes.
Date Probable causes [2] Quaternary: Holocene extinction: c. 10,000 BC – Ongoing: Humans [3] Quaternary extinction event: 640,000, 74,000, and 13,000 years ago: Unknown; may include climate changes, massive volcanic eruptions and Humans (largely by human overhunting) [4] [5] [6] Neogene: Pliocene–Pleistocene boundary extinction: 2 Ma
Denudation chronology is the study of the long-term evolution of topography seen as sequence. Denudation chronology revolves around episodes of landscape-wide erosion , better known as denudation . The cycle of erosion model is a common approach used to establish denudation chronologies.
Tectonic uplift results in denudation (processes that wear away the earth's surface) by raising buried rocks closer to the surface. This process can redistribute large loads from an elevated region to a topographically lower area as well – thus promoting an isostatic response in the region of denudation (which can cause local bedrock uplift).
The model achieved its greatest popularity in the 1900–39 period when numerous studies on denudation chronology based on the model were published. In these studies usually two to five erosion cycles were identified. The approach of doing denudation chronology with the cycle of erosion model lost popularity from the 1930s onward. [21]
Extinction occurs at an uneven rate. Based on the fossil record, the background rate of extinctions on Earth is about two to five taxonomic families of marine animals every million years. [c] The Oxygen Catastrophe, which occurred around 2.45 billion years ago in the Paleoproterozoic, is plausible as the first-ever major extinction event.