Exam 13: The Ocean Floor

The most extensive mountain range on Earth extends for about 65,000 kilometers on the ocean floor and is known as the_______ .

Why are there virtually no sediments at ocean ridges, even when they are close to land?

The gently sloping submerged surface extending from the shoreline toward the deep ocean is termed the______ .

Deep sea trenches are important features for plate tectonic studies because______ .

Most of the world's landmass is in the_______ hemisphere.

Examine Figure 13.B from Earth Science, 14e below. Briefly explain the main points of Charles Darwin's hypothesis on coral atoll formation. Have we tested his hypothesis and is it still thought to be correct today? Can you think of another possible explanation that would explain the origin of such coral atolls?

The most important economic mineral resource extracted from the seafloor today is_______ .

Ocean ridges form because ______.

Sailors in the 16^th- 18^th century dreaded "rounding the horn" of South America because of strong winds and heavy seas. Cape Horn is about latitude 55°S at the tip of South America. These sailors were using a passage from the Atlantic to Pacific Ocean that was actually a stormy ocean now often called______ .

The Ocean is largest.

Sand, silt, and clays deposited on the ocean floor are described as _______ sediments.

Abyssal plains are very flat because ______.

A geologist is studying sediments on land that were originally deep sea sediments. She finds the minerals zircon and garnet in the sediments, which could only come from a continental region. These sediments must be ______.

_______ does not accumulate below 4500 meters depth because it is highly soluble in seawater below that depth.

Give the correct type of ocean floor sediment for each phrase. -Manganese nodule

The lowest point on earth is in the_______ Ocean.

Subduction of oceanic lithosphere at the trenches sometimes comes pieces of both the continental and oceanic lithosphere to break off and pile up to produce______ .

The most important economic resource in the ocean today is_______ .

When organisms living in seawater grow shells, the ratio between the isotopes of oxygen ¹⁸O/¹⁶O. trapped in their shell is dependent on the sea temperature. Why might geologists collect these sea shells from deep- sea sediments that are Pleistocene in age and measure their oxygen isotope ratios?

_______ sediment consists of shells and hard parts of marine organisms.