英和和英

名詞

omar (plural omars)

1. A glacial erratic piece of (typically smooth) dark siliceous greywacke that exhibits a hemispherical pit or hole (as a result of selective dissolution of carbonate concretions within the greywacke), originating in the Omarolluk Formation and carried by glaciers throughout Canada and the United States.
   • 1991, Current Research, page 137:

     […] Omarolluk Formation of the Belcher Islands and mapped their distribution (mostly for those erratics showing concretions or concretion pits) in Ontario and western Canada. The omars are widespread in northern Ontario and have been [...]

   • 1997, Arkansas Archeological Survey Research Series, page 26:

     […] Omarolluk Formation , which outcrops throughout the eastern part of Hudson Bay. These "dark erratics" or "omars", have been used extensively as indicators of ice flow direction. Omars are common throughout the deposits of the [...]

   • 2000, Géographie Physique et Quaternaire, volume 54, page 268:

     [...] Omarolluk Formation serves to distinguish omars from wacke clasts derived [...] an omar dispersal "limit" in Northern Ontario is difficult to reconcile [...]

   • 2005, Minnesota Conservation Volunteer, volume 68, page 24:

     [...] an omar, a distinctive kind of graywacke - dark gray, fine-grained sandstone with concretions of calcium carbonate. Omars range in dimension from the size of your fist to the size of your skull. Only one source is known : the Omarolluk [...]

   • 2017, John Menzies, Jaap van der Meer, Past Glacial Environments, page 700:

     Omarolluk Formation clasts ('omars') from the Belcher Islands in Hudson Bay, Canada (Prest, 1990).