Omarolluk

Omar
An Omar with a hemispherical void in its side.
General
Category	Native Minerals

cupstone

Omarolluks, sometimes shortened to "omars," are a distinctive type of glacial erratic that consists of dark siliceous greywacke and exhibits prominent rounded, often deep, hemispherical voids and pits. The hemispherical voids and pits result from the selective dissolution of carbonate concretions within the greywacke. The greywacke, of which Omars consist, is identifiable by its low metamorphic grade and the 10%–40% rock fragments, distinctive volcanic clasts, and spherical carbonate concretions that it contains. Omars are typically rounded and range in size from pebbles to boulders. Their rounded shape, whether found in glacial tills or glacial-fluvial (outwash) gravels, indicate that they were eroded from pre-existing littoral or fluvial deposits. Omars are typically found associated with granules and pebbles of oolitic jasper that were transported from the Belcher Islands in Hudson Bay, Canada.^[1]^[2]^[3]

The name given these glacial erratics refer to their source, which is the Proterozoic Omarolluk Formation in the Belcher Islands in southeast Hudson Bay. The Laurentide Ice Sheet eroded omars from the Belcher Islands, an archipelago limited to only about a quarter of 1% of Hudson Bay. Glaciers moved omars from the southeastern part of Hudson Bay to central Canada and into the U.S. where they were deposited on moraines. Because scientists know precisely where they came from they are very valuable in documenting the movement of glaciers.^[2]^[4]^[5]

References

↑ Donaldson, A. and V.K. Prest (1997) Criteria for recognizing omars, widely dispersed indicators of Pleistocene history in North America. GAC/MAC Abs. 22:40, Ottawa.
1 2 Prest, V.K., J.A. Donaldson, and H.D. Mooers (2000) The omar story: the role of omars in assessing glacial history of west-central North America. Géographie Physique et Quaternaire 54(3):257-270.
↑ Mooers, H.D., and J.D. Lehr (1998) Terrestrial record of Laurentide Ice Sheet reorganization during Heinrich events: Reply. Geology. 26(7):668-669.
↑ Dutch, S. (n.d.) Leaverites - Features in Sedimentary Rocks. Natural and Applied Sciences, University of Wisconsin, Green Bay, Wisconsin Downloaded October 28, 2009
↑ Wilson, G. (2007) An omar (siltstone erratic). Turnstone Geological Services Ltd, Campbellford, Ontario, Canada. Downloaded October 28, 2009

Prehistoric technology

Tools

Farming

Food processing

Hunting

Arrow Boomerang throwing stick Bow and arrow history Nets Spear Spear-thrower baton harpoon woomera Schöningen Spears
Projectile points	Arrowhead Bare Island Cascade Clovis Cresswell Cumberland Eden Folsom Lamoka Manis Site Plano Transverse arrowhead
Systems	Game drive system Buffalo jump

Toolmaking

Other tools

Architecture

Ceremonial	Göbekli Tepe Kiva Standing stones megalith row Stonehenge Pyramid
Dwellings	Neolithic architecture British megalith architecture Nordic megalith architecture Burdei Cave Cliff dwelling Dugout Hut Quiggly hole Jacal Longhouse Mud brick Mehrgarh Neolithic long house Pit-house Pueblitos Pueblo Rock shelter Blombos Cave Abri de la Madeleine Sibudu Cave Stone roof Roundhouse Stilt house Alp pile dwellings Wattle and daub
Water management	Check dam Cistern Flush toilet Reservoir Water well
Other architecture	Archaeological features Broch Burnt mound fulacht fiadh Causewayed enclosure Tor enclosure Circular enclosure Goseck Cursus Henge Thornborough Oldest buildings Megalithic architectural elements Midden Timber circle Timber trackway Sweet Track

Arts and culture

Material goods	Baskets Beadwork Beds Chalcolithic Clothing/textiles timeline Cosmetics Glue Hides shoes Ötzi Jewelry amber use Mirrors Pottery Cardium Grooved ware Linear Jōmon Unstan ware Sewing needle Weaving Wine Winery wine press
PrehistArt	Art of the Upper Paleolithic Art of the Middle Paleolithic Blombos Cave List of Stone Age art Bird stone Bradshaw rock paintings Cairn Carved Stone Balls Cave paintings painting pigment Cup and ring mark Geoglyph Golden hats Guardian stones Megalithic art Petroform Petroglyph Petrosomatoglyph Pictogram Rock art Stone carving Sculpture Statue menhir Stone circle list British Isles and Brittany Venus figurines
Burial	Burial mounds Bowl barrow Round barrow Mound Builders culture U.S. sites Chamber tomb Severn-Cotswold Cist Dartmoor kistvaens Clava cairn Court tomb Cremation Dolmen Great dolmen Funeral pyre Gallery grave transepted wedge-shaped Grave goods Jar burial Long barrow unchambered Grønsalen Megalithic tomb Mummy Passage grave Rectangular dolmen Ring cairn Simple dolmen Stone box grave Tor cairn Tumulus Unchambered long cairn
Other cultural	Astronomy sites lunar calendar Behavioral modernity Origin of language Prehistoric medicine trepanning Evolutionary musicology music archaeology Prehistoric music Alligator drum flutes Divje Babe flute gudi Prehistoric numerals Origin of religion Paleolithic religion Prehistoric religion Spiritual drug use Prehistoric warfare Symbols symbolism

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Omarolluk

See also

References