Exam 22: Amazing Ice: Glaciers and Ice Ages

The central glacier in the figure below once stretched all the way to the farthest ground moraine.What type of glacier was it?

You are hiking in Illinois and notice several ringlike hills composed of till.You climb to the top of one,look toward the south,and see several more hills in the distance.In which direction did the glacier advance?

You are hiking in your favorite forest when you encounter a surface that appears to have very fine scratches in it.What are these features?

Valleys carved by glaciers tend to be shaped like the letter ________,whereas valleys carved by water tend to be shaped like the letter ________.

Ice is a substance with a high albedo,which means it ________.

Cirques,horns,and arêtes form from glacial ________,whereas moraines,erratics,and till form from glacial ________.

The Carboniferous Period was a time when swamps and forests dominated Earth.What was the climate like during this period?

Wind blows finer particles long distances from glacial environments,where they settle out to form ________.

If glaciers carry a mixture of different clast sizes,why are glacial outwash deposits layered?

The effect of periodic changes in Earth's orbital eccentricity and magnitude and direction (precession)of its axial tilt on the advance and retreat of ice sheets was first proposed by ________.

Cirques and horns are features associated with ________.

Today,continental glaciers are limited to Antarctica and ________.

Sediments deposited directly by glaciers as they melt are characterized by ________.

The current interglacial interval began a little more than ________ years ago.

At depths of greater than 60 m,ice moves by plastic deformation.What causes this transition from brittle to ductile behavior?

Currently,almost all the glaciers on Earth are in a state of retreat,which means that the rate of ________ is less than the rate of ________.

An angular peak surrounded by three or more bowl-shaped depressions formed by a mountain glacier is termed a(n)________.

Glacial ice exhibits ________ behavior near the top but ________ behavior beneath a depth of 60 m.

The Mars rover Curiosity has recently found evidence that there was liquid water on the planet's surface at some point in its history.Because we have not found any liquid water on the planet today,what does this imply about Mars?

At the present,glaciers cover about ________ of the surface of the continents.