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The Quaternary glaciation produced more lakes than all other geologic processes combined. The reason is that a continental glacier completely disrupts the preglacial drainage system . The surface over which the glacier moved was scoured and eroded by the ice, leaving many closed, undrained depressions in the bedrock.
A minor series of glaciations occurred from 460 to 430 Ma, and there were extensive glaciations from 350 to 289 Ma. The Late Cenozoic Ice Age has seen extensive ice sheets in Antarctica for the last 34 Ma. During the last 3 Ma, ice sheets have also developed on the northern hemisphere.
The timeline of glaciation covers ice ages specifically, which tend to have their own names for phases, often with different names used for different parts of the world. The names for earlier periods and events come from geology and paleontology. The marine isotope stages (MIS) are often used to express dating within the Quaternary.
Violet: The extent of the Alpine ice sheet in the Würm glaciation. Blue: The extent in earlier ice ages. The Würm glaciation or Würm stage (German: Würm-Kaltzeit or Würm-Glazial, colloquially often also Würmeiszeit or Würmzeit; cf. ice age), usually referred to in the literature as the Würm [1] (often spelled "Wurm"), was the last glacial period in the Alpine region.
Violet: Extent of the Alpine ice sheet in the Würm glaciation.Blue: Extent in earlier ice ages. The Late Pleistocene is an unofficial age in the international geologic timescale in chronostratigraphy, also known as the Upper Pleistocene from a stratigraphic perspective.
The Quaternary Period follows the Neogene Period and extends to the present. The Quaternary covers the time span of glaciations classified as the Pleistocene, and includes the present interglacial time-period, the Holocene. This places the start of the Quaternary at the onset of Northern Hemisphere glaciation approximately 2.6 million years ago .
The Mid-Pleistocene Transition (MPT), also known as the Mid-Pleistocene Revolution (MPR), [1] is a fundamental change in the behaviour of glacial cycles during the Quaternary glaciations. [2] [3] The transition lasted around 550,000 years, [4] from 1.25 million years ago until 0.7 million years ago approximately, in the Pleistocene epoch. [5]
For example, instead of two glaciations having occurred prior to the Illinoian Stage, researchers found that 11 distinct glaciations had occurred. In addition, what was presumed to have been a single volcanic ash bed, which was used to correlate and differentiate between Kansan and Nebraskan glacial deposits, was found to be three volcanic ash ...