Glacier

ICE AGE on Earth! Glaciation, Sea Level Rise, Lost Civilizations, Sundaland, the Flood

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• published: 11 Jul 2013
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Currently, the earth is in an interglacial period, which marked the beginning of the Holocene epoch. The current interglacial began between 10,000 and 15,000 years ago, which caused the ice sheets from the last glacial period to begin to disappear. Remnants of these last glaciers, now occupying about 10% of the world's land surface, still exist in Greenland and Antarctica. Global warming has exacerbated the retreat of these glaciers.[3] During the glacial periods, the present (i.e. interglacial) hydrologic system was completely interrupted throughout large areas of the world and was considerably modified in others. Due to the volume of ice on land, sea level was approximately 120 meters lower than present. The evidence of such an event in the recent past is robust. Over the last century, extensive field observations have provided evidence that continental glaciers covered large parts of Europe, North America, and Siberia. Maps of glacial features were compiled after many years of fieldwork by hundreds of geologists who mapped the location and orientation of drumlins, eskers, moraines, striations, and glacial stream channels. These maps revealed the extent of the ice sheets, the direction of flow, and the locations of systems of meltwater channels, and they allowed scientists to decipher a history of multiple advances and retreats of the ice. Even before the theory of worldwide glaciation was generally accepted, many observers recognized that more than a single advance and retreat of the ice had occurred. Extensive evidence now shows that a number of periods of growth and retreat of continental glaciers occurred during the ice age, called glacials and interglacials. The interglacial periods of warm climate are represented by buried soil profiles, peat beds, and lake and stream deposits separating the unsorted, unstratified deposits of glacial debris. There have been five known ice ages in the Earth's history, with the Earth experiencing the Quaternary Ice Age during the present time. Within ice ages, there exist periods of more severe glacial conditions and more temperate referred to as glacial periods and interglacial periods, respectively. The Earth is currently in an interglacial period of the Quaternary Ice Age, with the last glacial period of the Quaternary having ended approximately 10,000 years ago with the start of the Holocene epoch. The last glacial period, popularly known as the Ice Age, was the most recent glacial period within the current ice age occurring during the last years of the Pleistocene, from approximately 110,000 to 10,000 years ago.[1] During this period there were several changes between glacier advance and retreat. The maximum extent of glaciation within this last glacial period was approximately 22,000 years ago. While the general pattern of global cooling and glacier advance was similar, local differences in the development of glacier advance and retreat makes it difficult to compare the details from continent to continent (see picture of ice core data below for differences). From the point of view of human archaeology, it falls in the Paleolithic and Mesolithic periods. What is glaciotectonism? Some glacial deposition processes produce unsorted material, whereas fluvioglacial processes produce sorted and stratified material. Glacitectonic processes disrupt and deform these sediments and the bedrock below, either at the base of the glacier or in front of it. We have found that this process mainly occurs where glaciers are known to be surging and/or the sediments involved are frozen. In proglacial positions (in front of glaciers), coherent blocks of sediment and bedrock can be displaced vertically and horizontally by a glacier, producing both folding and faulting. This is known as proglacial glacitectonics and includes both ductile and brittle failure of materials.