How the Earth Was Made: Deepest Place on Earth Video Questions

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The rocks subducted at the Marianas Trench are the oldest known sea floor. How old were the pieces of crust drilled from the Marianas Trench?

170 million years

What is the rate of spreading revealed by the magnetized rocks?

2 in/yr

During the Trieste's descent, at what depth did darkness become total?

3000 feet

What was the Trieste's depth gauge reading?

35,800 feet

How deep was the ocean 200 mi off the coast of Guam?

4,475 fathoms or nearly 5 miles

To date, less than ____% of the world's oceans has been explored?

5

According to the narrator, pressure at the Challenger Deep is the equivalent to being squeezed on all sides by the weight of...

50 Jumbo Jets

How "staggeringly deep" is the Challenger Deep?

7 miles

Just before landing, what did the divers see on the bottom of the trench?

A bottom-dwelling flatfish

What prevented detailed observations of the enormous trench?

A cloud of fine, powdery

Where were strange "zebra stripes" of magnetic rocks discovered?

Along the Mid-Atlantic Ridge

Along with the Trieste's lights, what else lit up the abyss?

Bioluminecent animals

According to the narrator, the Marianas Trench was a small part of a planet-wide system of underwater...

Canyons

In magma, what locks magnetic minerals in position?

Cooling

Geologists know the earth to be a giant ____, with a north and a south pole.

Magnet

According to the narrator, what was MAD during the Cold War?

Magnetic Anomaly Detector

What was found in the ocean along the shallower, western edge of the Marianas Trench?

Mud Volcanoes

What was unusual about the Marianas Islands, a chain of volcanoes lying 200 miles west of the trench?

The island chain mirrored the trench's exact shape

What happens every 300,000 years?

The magnetic field flips 180 degrees, and a north pointing compass would swing south

What happened 2 hours into the Trieste's dive at a depth of 20,000 ft.?

The outer window cracked

What did geologists discover about the ridges in the 1960s?

They were created by magma upwelling from deep underground

In 1960, who commanded the Trieste and attempted to dive 7 miles to the bottom of the trench?

Don Walsh

According to the narrator, what transformative discovery was made by Cold War seismometers?

Earthquakes clustered along the ocean's ridges and trenches

Which giant underwater mountain range lies parallel to the Marianas Trench on the opposite side of the ocean?

East Pacific Ridge

How can the Pacific Plate's movement be tracked today?

GPS

In the 1950s and 60s, who led a team of geologists that compiled sonar data from all of the world's oceans?

Harry Hess of Princeton

What was being emitted from the rock pillars discovered in 1977 by Dudley Foster and his crew?

Hot, toxic gas

What is predicted for Australia in millions of years?

It will crash into North America

How is the extraordinary depth of the Marianas Trench explained?

Its crust is oldest and heaviest

What ingredient helps the magma at the ocean trenches to melt and form volcanoes?

Ocean Water

Which plate is largest and fastest moving?

Pacific Plate

50 million years ago, the Pacific Plate slipped under the...

Philippine Plate

What extraordinary new theory was born?

Plate Tectonics

The solid crust is broken into a series of slabs called ____, which grind past each other triggering earthquakes.

Plates

In 1874, how did the British surveyors of HMS Challenger map the ocean floor?

Rope and lead weights

In 1951, which technique, originally developed to detect lurking submarines, showed that the Challenger "deep hole" was really a trench twice the length of California?

SONAR

Which soft rock was ground up in the subduction zone?

Serpentine

What occurs where two tectonic plates collide, pushing the heavier plate beneath the lighter plate into the mantle?

SubductionWhat was found in the ocean along the shallower, western edge of the Marianas Trench?

The Marianas Trench devours the Pacific Plate at a rate of 3 in/yr, about as fast as...

a human fingernail grows

What prevents large earthquakes at the Marianas Trench?

lubricating mud

The 40,000 mi network of underwater mountain ranges, earth's largest geologic feature, rings the globe like...

seams on a baseball

With reversals of magnetic polarity, the sea floor acts like a...

tape recorder


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