How the Earth Was Made: Deepest Place on Earth Video Questions
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 silt
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 about the movement of Earth's crust?
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?
Subduction
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