• glacial deposits
  • In other parts of Donegal, scientists have discovered rocks that began life as glacial deposits, demonstrating that at this early period, part of what was to become Ireland was in the grip of an ice age. (wikipedia.org)
  • There are few areas in which the earlier drifts from the glacial deposits of the Pre-Ilionian or Illinoian stages are exposed at the surface. (wikipedia.org)
  • Furthermore, these regions of older drift are maturely drained, because the streams have had a longer time to evolve into an efficient drainage system compared with the streams flowing in areas covered by younger glacial deposits. (wikipedia.org)
  • Howard Hobbs has proposed that the Pre-Illinoian glacial deposits in southeastern Minnesota are actually younger Illinoian glacial deposits. (wikipedia.org)
  • intermediate
  • Intermediate depression, comprising ternary deposits The soils are very varied, though they are mostly sandy, deep and generally not very fertile. (wikipedia.org)
  • For this reason, even for the deposits with sharp boundaries, a clear definition of the cut-off grade and distinction between ore and gangue due to dilution during mining, the presence of intermediate layer and the limitation of mining in a selective way are essential. (wikipedia.org)
  • mineral
  • The far north Queensland mining magnate, John Moffat, buoyed by reports from Atherton and others of the discovery of payable mineral deposits, visited the area in October 1888 and subsequently acquired the mineral rights over a considerable amount of the Chillagoe/Mungana area. (wikipedia.org)
  • citation needed] The uncertainty in estimating the tonnage of mineral resources or ore reserves depends on a number of factors, and the uncertainty of definition of the deposit boundaries is one of them. (wikipedia.org)
  • Generally, these boundaries are determined by mineral grade rather than geological properties: deposit boundaries are chosen based on the cut-off grade. (wikipedia.org)
  • deposition
  • This torrential-stream deposit, close to enlaced rivers, laid to the deposition of sandy-clayey materials, with a variable iron content, coming from a lateritic weathering, of the French "Massif Central" granites. (wikipedia.org)
  • Chad
  • 17.780889 The Bodélé Depression (pronounced [bɔ.de.le]), located at the southern edge of the Sahara Desert in north central Africa, is the lowest point in Chad. (wikipedia.org)
  • As the wind sweeps between the Tibesti and the Ennedi Mountains in Northern Chad, it is channeled across the depression. (wikipedia.org)
  • upper
  • Late Cenozoic continental shelf and upper slope deposits consist primarily of siItstone and mudstone and subordinate arkosic and lithic Wackes. (geoscienceworld.org)
  • continental
  • Deposits left by the continental ice sheets advancing from these three centers reflect the characteristics of the rocks over which they passed. (wikipedia.org)
  • wind
  • The same researchers who in 2004 more accurately determined the speed of wind through the depression also published in 2006 work showing that more than half of the dust needed for fertilizing the Amazon Rainforest is provided by the Bodélé depression, depositing up to 50 million tonnes in South America per year. (wikipedia.org)
  • layers
  • The volcano of Sete Cidades is distinguished by two stratigraphic layers: The inferior group includes the oldest deposits associated with subaerial eruptions occurring more than 200,000 years B.C. This period of activity was essentially effusive producing basalt lava flows of trachyte. (wikipedia.org)
  • east
  • The research also shows that, contrary to what was previously thought, most of the Saharan dust that reaches the east coast of the United States originates from a single source-the Bodele depression. (wikipedia.org)