The present-day tilt of earth's axis of rotation is $23.5^{\circ}$. What would be the result of more tilt, as shown here?

A. high latitudes would receive less direct sunlight during the summer, causing cooler temperatures

B. a decrease in glaciers

C. a decrease in the effects of the seasons

D. all of these

Which among the following statements regarding the discovery of DNA is true?

What are these sharp, glacially carved ridges?

A. cirque

B. arate

C. hogback

D. razorback

E. flatiron

What happens when a glacier encounters the sea or a lake?

A. the ice is more dense than water and so scrapes along the bottom

B. white icebergs float but blue icebergs sink to the bottom

C. large blocks of ice collapse off the front of the glacier and become icebergs

D. rocks released from melted icebergs float on the water surface

E. all of these

What is the origin of curved ridges (R on this flgure) in the Great Lakes area?

A. folds produced during a continental collision

B. paths of ancient rivers

C. piles of sediment deposited by retreating glaciers

D. remnants of a meteoroid impact

Which of the following is NOT a type of evidence left behind by glaciers?

A. scratched and polished bedrock

B. scattered stones (dropstones) in fine-grained sediment

C. changes in the isotopic compositions of marine shells

D. V-shaped valleys

E. all of these are evidence left behind by glaciers

What percentage of the world’s glacial ice is included in the Antarctic Ice Sheet?

Which of the features labeled on this figure is a drumlin?

A. A

B. $\mathrm{B}$

C. C

D. D

Using this plot of annual peak discharge, what is the probability each year that a flood of 1,000 cubic meters per second will occur?

A. 1 in 1,000 , or $0.01 \%$

B. 1 in 100 , or $1 \%$ (100-year flood)

C. between 10 and $20 \%$

D. more than $20 \%$

What typically happens when tributaries join the main river?

A. channel size increases

B. water velocity increases

C. the amount of discharge increases

D. total sediment load increases

E. all of these

What could cause this stream to deposit sediment?

A. a rise in base level, such as a rise in sea level

B. subsidence of the land, producing slopes that are less steep

C. both a rise in base level or subsidence of the land

D. none of these

What is the end of a river called?

What is the discharge of the stream shown in the accompanying figure if the velocity is $1.5$ meters per second?

A. 3,000 cubic meters per second

B. 1,500 cubic meters per second

C. 1,250 cubic meters per second

D. 125 cubic meters per second

E. none of these

What is the North American continental drainage divide?