Q 01/05

Which river carved Arizona's Grand Canyon, cutting through a mile of rock in five to six million years?

A) Rio Grande

B) Snake

C) Colorado

D) Columbia

Answer · why

C) Colorado

The Colorado did not work alone: side streams and collapsing cliffs widened the canyon to as much as 18 miles across.

Q 02/05

What name was given to the 1930s disaster in which wind stripped bare topsoil from the American Great Plains?

A) Dust Bowl

B) Tornado Alley

C) Rust Belt

D) Badlands

Answer · why

A) Dust Bowl

Dust Bowl was coined by an Associated Press editor after the Black Sunday storms of April 1935, and the damage reached about 100 million acres.

Q 03/05

Which famous waterfall has retreated almost seven miles upstream since the last ice age by wearing away its own ledge?

A) Victoria Falls

B) Angel Falls

C) Iguazu Falls

D) Niagara Falls

Answer · why

D) Niagara Falls

Niagara Falls once wore back more than three feet a year; engineering works have slowed that to about one foot.

Q 04/05

Which is missing from the Moon, along with liquid water, so that weather never wears away the Apollo bootprints?

A) Sunlight

B) An atmosphere

C) Solid bedrock

D) Impact craters

Answer · why

B) An atmosphere

An atmosphere would bring wind and rain; without one, the Moon's surface is worn only by micrometeorites that slowly soften and round its features.

Q 05/05

Which Chinese waterway picks up so much silt crossing the Loess Plateau that its rising bed causes disastrous floods?

A) Yellow River

B) Yangtze River

C) Mekong River

D) Pearl River

Answer · why

A) Yellow River

Yellow River water gets its color, and the river its name, from that silt, which settles on the bed and slowly builds natural dams.