1.Scientists say that glaciers flow. What does this mean? A) The ice spins slowly in circles, because of the Coriolis force from Earth’s rotation.B) The ice moves slowly downhill, because it is so cold and dense that it sinks through the rocks beneath.C) The ice is almost warm enough to melt, and so the ice deforms slowly something like the rocks in the mantle or a chocolate bar in your pocket.D) The ice is so brittle that it crumbles when shaken by the wind, and the pieces roll downhill.E) The ice kicks back and watches the football game on TV.Feedback: Continue
Materials warmed almost but not quite to their melting point can deform without breaking or melting. We saw this with the great convection cells in the mantle, back in unit 2, and we meet it again with ice. If you list the temperature of the ice in degrees F, it is a lot colder than the mantle, or iron heated by a blacksmith, or achocolate bar in your pocket. But, the ice has been warmed from absolute zero almost to the melting temperature, just like the mantle and the iron and the chocolate, so the stress from gravity can cause the ice to deform or flow.Correct Answer(s):C Points Earned: 1.0/1.0 2.Pieces of bedrock from Canada, north of Lake Superior, are spread across large areas of Wisconsin and Minnesota in the US, even though Lake Superior sits between the Canadian source of the rocks and the US places that the rocks now are. How do geologists explain this?
Points Earned: 1.0/1.0
You've reached the end of your free preview.
Want to read all 129 pages?
- Spring '12
- Subduction, Delta Airlines, Appalachians