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Information and IdeasMediumFinding supporting a glacial origin

Information and Ideas practice question

A geologist claims that the valley was carved by a glacier rather than by a river.

Which finding, if true, would most directly support the geologist's claim?

  1. A. The valley has a broad U-shaped cross-section, and its floor is scattered with boulders of a rock type found only 80 kilometres to the north.Correct
  2. B. A river runs along the valley floor today.
  3. C. The valley is more than 40 kilometres long.
  4. D. The valley's soil is unusually fertile.

Answer: A. The valley has a broad U-shaped cross-section, and its floor is scattered with boulders of a rock type found only 80 kilometres to the north.

A U-shaped profile and far-travelled boulders are classic signs of glacial carving and transport.

Why the other answers are wrong

B. A river runs along the valley floor today.
A present-day river doesn't show what carved the valley, and if anything points the other way.
C. The valley is more than 40 kilometres long.
Length doesn't distinguish glacial from river valleys.
D. The valley's soil is unusually fertile.
Fertility doesn't distinguish them either.

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