Oceans

Why are Earth’s oceans salty?

• Rain washed salts into them.

• They contain a lot of water vapor.

• Algal blooms in the ocean produced salt.

Which description best characterizes the seafloor?

• A. mostly flat

• B. full of life-forms

• C. similar to the continents

Ocean waves move water

• to form tides.

• long distances.

• in a circular motion.

Ocean surface currents are caused by

• wind.

• gravity.

• density.

Density currents move ocean water

• upward.

• downward.

• horizontally.

Which situation describes a point-source ocean pollutant?

• nitrates mixed in runoff

• a nearby volcanic eruption

• oil spills from several ships

What causes coral bleaching?

• slight changes in water temperature

• an increase in carbon dioxide in the water

• strong winds that blow for long periods of time

The salinity of Earth’s oceans is the result of

• ancient volcanism.

• point-source pollutants.

• weathering by acid rain.

• condensation of water vapor.

Seafloor topography

• A. is the result of the Coriolis effect.

• is a vast expanse of only abyssal plains.

• includes plains, mountains, and trenches.

• was produced by upwelling and surface currents.

Density currents are the result of

• upwelling during cold months.

• wind blowing over a large area

• changes in salinity or temperature.

• particle circulation in surface waves.