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A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate between glacial periods. The Last Glacial Period ended about 15,000 years ago. [1]
Within ice ages, there exist periods of more severe glacial conditions and more temperate conditions, referred to as glacial periods and interglacial periods, respectively. The Earth is currently in such an interglacial period of the Quaternary glaciation, with the Last Glacial Period of the Quaternary having ended approximately 11,700 years ago.
Last Glacial Period, not to be confused with the Last Glacial Maximum or Late Glacial Maximum below. (The following events also fall into this period.) 48,000–28,000: Mousterian Pluvial wet in North Africa 26,500–19,000: Last Glacial Maximum, what is often meant in popular usage by "Last Ice Age" 16,000–13,000
Late Cenozoic Ice Age, the geologic period of the last 33.9 million years Little Ice Age , a period of relative cold in certain regions from roughly 1450–1480 Pleistocene , a geologic epoch, often colloquially referred to as the "Ice Age", that includes the world's most recent repeated glaciations (2,580,000 to 11,700 years ago)
An illustration of ice age Earth at its glacial maximum. A "greenhouse Earth" is a period during which no continental glaciers exist anywhere on the planet. [6] Additionally, the levels of carbon dioxide and other greenhouse gases (such as water vapor and methane) are high, and sea surface temperatures (SSTs) range from 28 °C (82.4 °F) in the tropics to 0 °C (32 °F) in the polar regions. [7]
Initially the glacial/interglacial cycle length was about 41,000 years, but following the Mid-Pleistocene Transition about 1 Ma, it slowed to about 100,000 years, as evidenced most clearly by ice cores for the past 800,000 years and marine sediment cores for the earlier period. Over the past 740,000 years there have been eight glacial cycles. [7]
The categorisation of the past into discrete, quantified named blocks of time is called periodization. [1] This is a list of such named time periods as defined in various fields of study. These can be divided broadly into prehistorical periods and historical periods (when written records began to be kept).
Movement (of ice) in a constant direction. Fracture Brittle failure (breaking of ice) under the stress raised when movement is too rapid to be accommodated by creep. It happens, for example, as the central part of a glacier moves faster than the edges. Glacial landform Collective name for the morphologic structures in/on/under/around a glacier ...