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Topic: The Glacial Erratics


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 Glacial erratic - Wikipedia, the free encyclopedia
A glacial erratic is a piece of rock carried by glacial ice some distance from the rock outcrop from which it came.
Erratics were once considered evidence of a biblical flood, but in the 19th Century scientists gradually came to accept that erratics pointed to an ice age in Earth's past.
Cluster of erratics found high on the slopes of Red Mountain shown in the foreground; these were trapped in glacial ice and "rafted in" on the flood of Lake Lewis.
en.wikipedia.org /wiki/Glacial_erratic   (476 words)

  
 Boulders
In Iowa, glacial erratics are commonly observed where glacial deposits occur at the land surface, primarily in the north-central and northeastern parts of the state.
Erratics from a given area are nearly always more numerous near their source and diminish in number with distance from the source.
Glacial erratics are known to have been transported great distances by the Pleistocene-age ice sheets that covered the midcontinent region.
www.igsb.uiowa.edu /browse/boulders/boulders.htm   (1630 words)

  
 Glacial and Arid Landforms   (Site not responding. Last check: 2007-10-13)
A glacier is a large slow-moving mass of ice that moves due to gravity.
Polar glaciers are frozen to their bed and do not benefit from meltwater, relying on internal deformation rather than basal sliding, so their rates of movement are much slower.
Temperate glaciers have lag times ranging from a few years to a decade or more between the difference in mass balance and the advance or retreat of the glacier.
tesla.jcu.edu.au /Schools/Earth/EA1004/Geomorphology/Glaciers.html   (1184 words)

  
 10(af) Landforms of Glaciation
Glaciers have played an important role in the shaping of landscapes in the middle and high latitudes and in alpine environments.
The flow of an alpine glacier into a valley, causes the glacier to rapidly advance producing a swollen tongue of ice at the glacier's snout, known as a lobe.
Glacial erratics are large pieces of rock that have been transported away from their source areas by moving glacial ice sheets.
www.physicalgeography.net /fundamentals/10af.html   (1793 words)

  
 Glaciers and Glaciation
Glaciers are masses of ice that flow under the influence of gravity.
Glaciers are the largest reservoir of fresh water and contain about 2.15% of the world's water.
Glacial Erratics - Erratics are pieces of rock carried by a glacier and left stranded on bedrock of different composition.
www.geo.ua.edu /intro03/ice.html   (2571 words)

  
 Local Geology at Limper Geology Museum
Glacial erratics are pieces of rocks that are carried by glacial ice and are erratic because they do not match the bedrock in the area where they are found.
Because the glacial erratics that we find in southwestern Ohio come from such a large area, they consist of a wide variety of rock types, including numerous examples of igneous, sedimentary, and metamorphic rocks.
A common use of glacial erratics is for landscaping purposes.
www.users.muohio.edu /lingenla/lgm/erratic.htm   (141 words)

  
 Burnt Island's Glacial Erratics of the Lincoln Sill, Maine
Burnt Island's Glacial Erratics of the Lincoln Sill
A better explanation is that the boulders were brought to their current resting place by glacial ice and left as ice melted at the end of the last ice age, perhaps 15,000 years ago.
The Surficial Geologic Map of Maine (Thompson and Borns, 1985; Figure 7) shows by small fl arrows that scratches made by the glacier are oriented about 15 degrees east of south, indicating this to be the direction the ice moved.
www.state.me.us /doc/nrimc/mgs/explore/bedrock/sites/nov00.htm   (2203 words)

  
 Glacier - Wikipedia, the free encyclopedia
A glacier is a large, long-lasting river of ice that is formed on land and moves in response to gravity and undergoes internal deformation.
Glacial erratics are rounded boulders that were left by a melting glacier and are often seen perched precariously on exposed rock faces after glacial retreat.
The idea that the evidence of middle-latitude glaciations is closely related to the displacement of tectonic plates was confirmed by the absence of glacial traces in the same period for the higher latitudes of North America and Eurasia, which indicates that their locations were very different from today.
en.wikipedia.org /wiki/Glacial   (4884 words)

  
 ABSTRACT: Has the Northern Gaspe Peninsula ever been invaded by an ice Sheet from Québec-Labrador?
Glacial models proposed for Gaspé Peninsula have evolved from simple to complex, over the last century, on the origin and extent of the glacial ice cover.
However, glacial erosion appears to have been minimal on the coastal plateau at 300 - 400 m elevation - the back-walls of glacial cirques which incise the coastal plateau have not been breached by glacial erosion, and other large and medium scale forms (flyggbergs, roches moutonnées and glacial grooves are totally missing from the plateau surface.
The enigma of the rare occurrences of erratics from the eastern Gaspe Peninsula, interpreted as precambrian remains to be resolved, however.
cgrg.geog.uvic.ca /abstracts/CsikiHasGlacial.html   (875 words)

  
 Virtual Saskatchewan - Glacial Erratics
They know that glacial erratics, so named because they were sheared from northern bedrock and strewn across the prairie by glaciers, can offer clues to the location of valuable mineral deposits.
The hefty erratic was unearthed when rising lake waters burst over a ridge creating a powerful flow of water that cut Little Manitou Lake valley and exposed the Young and other erratics in the process.
Jones, meanwhile, says it's unfortunate so few of the large glacial erratics have been researched, given the natural and human history revealed by those that have.
www.virtualsk.com /current_issue/erratics.html   (961 words)

  
 The Temporal Doorway - Glacial Erratics
The name of the image comes from the geological phenomenon that results when a glacier that has been carrying boulders and rocks melts away.
Here, even some of the glacier, in the form of the ice cube, is left behind.
One of the areas of interest from a technical perspective is the use of a lighting array to create the soft shadows.
www.temporaldoorway.com /gallery/item/glacialerratics.htm   (351 words)

  
 ES 331/767 Lecture 4
Where glacial sediment is transported and deposited by mass movement or from water, stratification and sorting are usually evident.
Erratic boulders in Iowa, from the Iowa Geological Survey.
Glacial erratics of the Lincoln Sill from the Maine Geological Survey.
academic.emporia.edu /aberjame/ice/lec04/lec4.htm   (1305 words)

  
 Geotimes — September 2004 — Travels: Central Park
To the right is a glacially scoured outcrop of gneiss and schist on the west side of the park, with the Midtown skyline behind.
On Umpire's Rock you can observe a glacial trough, where the ice gouged away a smooth-edged path through the outcrop, as well as glacial erratics — rocks that are not original to the outcrop, but carried and deposited in that location by the moving ice.
Also visible are glacial grooves, thin lines cut out of the rock by the passage of rocks and sediment within the ice sheet, in two directions, which helps demonstrate the existence of separate glacial events.
www.agiweb.org /geotimes/sept04/Travels0904.html   (916 words)

  
 Landscape Features of Iowa
They are all that remain of a once higher glacial plain and are often capped with wind-blown loess and sand.
Glacial erratics are boulders of igneous and metamorphic rock, native to geographic regions well north of Iowa.
Glacial erratics of this formation are easily recognizable and may be found for many miles to the southeast.
www.igsb.uiowa.edu /Browse/landscap/landscap.htm   (1026 words)

  
 ISGS - Glacial Geology
Glacial geology is important in Illinois' most recent geologic past, the Quaternary Period (also called the Ice Age), during which continental glaciers repeatedly plowed across the state eroding and redistributing material and creating new landforms.
Today, Illinois is experiencing an interglacial episode, a relatively quiescent and warm interval of the Quaternary Period that allows the soil to form and crops to grow.
Quaternary geology encompasses both the cold and warm intervals and the glacial and nonglacial processes of the past 2 million years.
www.isgs.uiuc.edu /isgshome/glacial.htm   (83 words)

  
 Antarctica glacial history
Limited glacial erosion, thick glacial deposits in the north-western part of the hills and the relatively low altitude of the postglacial marine limit (9-7 m a.s.l.) suggested to Colhoun and Adamson (1992a) and Colhoun (1997) that the LGM ice sheet was not very thick and consequently did not extend far onto the continental shelf.
A mid-Holocene glacial readvance on northern James Ross Island, initially described by Rabassa (1983), was constrained by further stratigraphical and chronological evidence to have culminated in an at least 7 km ice-advance around 4.6 ka BP (Hjort et al., 1997).
The glacial retreat was partly controlled by the rise of sea level, which caused a relatively rapid collapse of the ice-sheet margin (Colhoun and Adamson, 1992a; Verkulich and Melles, 1992).
www.hi.is /~oi/quaternary_glacial_history_of_antarctica.htm   (15038 words)

  
 Oregon History - Glacial Erratics
The 90-ton glacial erratic rock at the top of this 1/4 mile-long trail is a stranger from a distant location- it was transported here thousands of years ago on an iceberg in the wake of a cataclysmic flood.
The floods also carried boulder-laden icebergs- as the ice melted and the floodwaters recede, boulders, called "glacial erratics," remained stranded in fields and prairies.
The boulder at the top of this trail is the largest known glacial erratic among the hundreds found in the Willamette Valley.Caption 1This large glacial erratic, composed of a metamorphic rock called argillite, was once much larger!
www.oregon.com /history/hm/glacial_erratics.cfm   (378 words)

  
 Glacial Geology
Glacial Erratics are large rocks carried by the Glacier, and dropped unceremoniously when the Glacier melts back.
The former are winding affairs from streams on or under a glacier, the latter are teardrop shaped affairs.
As mentioned before, Glacial erratics in the case of continential glaciers can be truly large, distinctive, and noticeable.
members.aol.com /scipioiv/glacialgeology.html   (984 words)

  
 Yellowstone National Park - Nature & Science
At the peak of this glacial era, roughly 25,000 years ago, prominent peaks like Mount Sheridan lay hidden underneath this icy blanket, while the tip of Mount Washburn and the thin ridgeline of the Absaroka Mountains barely peeked above this unrelenting sea of ice.
Among the broad hills and benches of Hayden Va l l e y, lake sediments of silt, sand, and gravel, covered in glacial till, remain from a time when the valley was covered by an ancient lake formed by an early ice dam.
Glacial ponds, striated hillsides, chiseled peaks, and polished mountain faces, all fashioned by the hand of ice, create some of the finishing touches on the spectacular landscape we see today.
www.nps.gov /archive/yell/pphtml/subnaturalfeatures13.html   (431 words)

  
 Journey to Alaska's Glaciers: How Do Glaciers Shape the Land?
Denali is a magnificent place to witness the awesome forces that glaciers have on the land.
We'll see massive u-shaped glacial valleys, sort through piles of glacial till, climb on glacial erratics, and wade in freezing cold glacial streams.
Glaciers change the land by eroding it in some places and depositing the rocks that are plucked up elsewhere.
www.iwebquest.com /alaska/webquest/glacier/shape.htm   (982 words)

  
 LINE On-line: Glaciation
These are glacial moraines that were formed at the edge of the glacial ice sheet.
Large boulders that have been moved by glaciers and, therefore, do not match underlying bedrock are known as glacial erratics.
These were formed by blocks of ice that separated form the main body of the glacier and became partially of wholly buries in glacial sediment.
www.chipr.sunysb.edu /eserc/longis/glacial.html   (960 words)

  
 Flat, but Not Dull—Understanding the Central Indiana Glacial Landscape
Beneath the scoured glacial debris, called "drift," is the land surface as it was before the presence of the glacier, about a million years ago.
Buried soils represent warm periods between glacial advances and are key markers for geologists sorting out the periods of time that the ice surged and retreated.
The understanding of glaciers and the geology of the region is tied to future planning for land use, the extraction of minerals, and the protection of the ground water we need for drinking and irrigation of farmland.
igs.indiana.edu /geology/topo/centralIndLandscape/index.cfm   (431 words)

  
 Glacial Moraine   (Site not responding. Last check: 2007-10-13)
When a glacier moves down a drainage or a valley, it pushes ahead of itself a large burden of debris, known as glacial till.
Later stages in the recession of the glacier are marked by end moraines.
These moraines hold more water than the surrounding glacial gravels in their soil and are therefore more heavily timbered than the surrounding area.
www.hanksville.org /daniel/geology/moraine.html   (172 words)

  
 Glacial Formations -- The Slackpacker's Geology Primer
Boulders perched atop a ridge, boulders resting on a tripod of small rocks, balancing rocks...usually these are metamorphic rock that have been dumped somewhere as glaciers moved, melted, or receded.
Glacial loess is a fine, wind-borne deposit of silt formed along the edge of a glacier.
The loess occurs where glacial outflows or smaller glaciers occurred.
www.slackpacker.com /glacial.html   (479 words)

  
 The Walter Bean Grand River Trail - Glacial Erratics
Between 23,000 and 14,000 years ago, the area now known as the Regional Municipality of Waterloo was covered by glacial ice hundreds of metres thick.
The glaciers flowed to this area from what is now central Quebec and northern Ontario, gathering blocks of bedrock along the way.
As the glaciers retreated, they left an assortment of rocks in their paths.
www.sju.ca /grt/glacial.htm   (294 words)

  
 Glacial Landforms Worksheet   (Site not responding. Last check: 2007-10-13)
Small islands in glacial, sediment-chocked streams are called _______.
According to the web site and the orientation of these drumlins, the direction of travel of the continental glacier was______________.
How is the location of glacial erratics used to tell the direction of past ice flow?
frontpage.velocity.net /wise/glacial_landforms_worksheet.htm   (130 words)

  
 Geology of Devils Postpile National Park
Glacial erratics are boulders carried by ice from points upstream.
Many of the erratics are different from the rocks they now rest upon, and some are composed of metamorphic rock which occurs only north of the Monument.
The erratics of metamorphic rock tell us that the ice carried them south from a distant source.
wrgis.wr.usgs.gov /docs/parks/depo/dpgeol12.html   (299 words)

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