Definitions

drift

drift

[drift]
drift, deposit of mixed clay, gravel, sand, and boulders transported and laid down by glaciers. Stratified, or glaciofluvial, drift is carried by waters flowing from the melting ice of a glacier. The flowing water sorts the particles, generally depositing layers of coarser particles nearer the point of origin. Till, or boulder clay, which makes up the greater part of the drift, is unstratified, consisting of disorganized heaps of rocks that range widely in size. Till is deposited directly by the glacier itself without water transport. The drift may take the form of a drumlin, a kame, an esker, a moraine, or an outwash plain; its thickness varies noticeably from place to place and is not dependent upon topographical factors. Presence of drift proved useful in establishing the existence of time periods when large parts of the surface of continents were covered with glaciers (see glacial periods). Large sections of continental Europe and North America are covered by drift.

Change in the pool of genes of a small population that takes place strictly by chance. Genetic drift can result in genetic traits being lost from a population or becoming widespread in a population without respect to the survival or reproductive value of the gene pairs (alleles) involved. A random statistical effect, genetic drift can occur only in small, isolated populations in which the gene pool is small enough that chance events can change its makeup substantially. In larger populations, any specific allele is carried by so many individuals that it is almost certain to be transmitted by some of them unless it is biologically unfavourable.

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The theory of continental drift is based on the concept that the continental and oceanic crusts are elipsis

Large-scale movements of continents over the course of geologic time. The first complete theory of continental drift was proposed in 1912 by Alfred Wegener, who postulated that a single supercontinent, which he called Pangea, fragmented late in the Triassic Period (approximately 250–200 million years ago) and that the parts began to move away from one another. He pointed to the similarity of rock strata in the Americas and Africa as evidence to support his hypothesis. Wegener's ideas received support from the concepts of seafloor spreading and plate tectonics beginning in the 1960s. The modern theory states that the Americas were joined with Europe and Africa until circa 190 million years ago, when they split apart along what is now the Mid-Atlantic Ridge. Subsequent tectonic plate movements took the continents to their present positions.

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Drift is a slow change and may refer specifically to:

In the literal sense of a change in position of a body:

  • Drifting (motorsport), which is a sport where drivers intentionally induce oversteer, to be judged on their technique.
  • Drift (railroad), which in railroading is the cutting off of power and using inertia alone to maintain forward movement.
  • The condition where a motor vehicle's rear wheels slip at a greater angle than the front wheels; see oversteer.
  • Intentional use of oversteer for faster cornering in low road surface traction conditions; see Opposite lock
  • Ice drift: drift of sea ice
  • Snow drift: a deposit of snow created by the wind

In science and technology:

In geography (In South Africa, drift is a synonym for ford):

In culture:

See also:

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