PLANET EARTH QUIZ #3

What led to the discovery of mid-ocean ridges?

Military maps of the seafloor created during World War II

Oceans are commonly warmer than adjacent land in the winter and cooler in the summer.

True

Sea levels has risen and fallen repeatedly in the geologic past, and coastlines have emerged and submerged throughout Earth's history.

True

The Mid-Oceanic Ridge system is Earth's largest mountain chain.

True

A glacier that forms in mountainous terrain and covers and area of less than 50,000 square kilometers is a(n) ____ glacier.

alpine

Samples of sediment can be collected from the seafloor using ____.

coring devices

Oceanic crust is ____ than continental crust and therefore ____ isostatically.

denser; sinks

Deep-sea currents are driven by ____.

differences in water density

Alpine glaciers are found on every continent on Earth.

false

The upward flow of water that carries cold water from the ocean depths to the surface is called_______________.

upwelling

Cycles identified by Milutin Milankovic´ are caused by ____.

variations in Earth's orbit and spin axis

Ocean water density depends on ____.

temperature and salinity

Most of the water that fills Earth's oceans came from ____.

the outer regions of the Solar System

Currently, Earth has only two ice sheets.

true

Glaciers form U-shaped valleys.

true

Pressure from the weight of overlying ice favors melting at the base.

true

Oceanic crust is thicker than continental crust.

False

The Pleistocene Glaciation began about ____ years ago.

2 million

Oceans cover about ____ percent of Earth's surface.

71

The ice sheets of Greenland and Antarctica contain ____ percent of the world's ice.

99

How could the Mid-Ocean Ridge system have caused sea level to rise in the past?

By bringing water up from the mantle

Granite is more dense than basalt.

False

The Mid-Oceanic Ridge rises high above the surrounding sea floor because new lithosphere forming at the ridge axis is ____ and of relatively ____ density.

hot; low

A thick mass of ice that floats on the ocean surface but is connected to and fed from a glacier on landis called a(n) ____.

ice shelf