Lesson 4: Continental Drift

Question 1

The continental drift hypothesis was developed in the early part of the 20th century by?

Answer 1

Alfred Wegener

Question 2

are like tiny magnets that point to the north magnetic pole as they crystallize from magma. The crystals record both the direction and strength of the
magnetic field at the time

Answer 2

magnetite crystals

Question 3

direction of the magnetic crystals

Answer 3

magnetic polarity

Question 4

the phenomenon of the magnetic pole that seemed to move but actually did not

Answer 4

apparent polar wander

Question 5

how did the continental drift theory become widely accepted

Answer 5

Dr. Harry Hess discovered seafloor spreading in 1960

Question 6

occurs at divergent plate boundaries which subsequently create mid-ocean ridges

Answer 6

Seafloor Spreading

Question 7

fit of the continents
match of mountain belts, rock types
distribution of fossils
paleoclimates
magnetic polarity movements

Answer 7

yes

Question 8

what did map makers notice?

Answer 8

fit of the continents

Question 9

weighted rope lowered overboard until it touched the ocean bottom; this old method is time-consuming and inaccurate

Answer 9

Sounding line

Question 10

type of sonar which measures depth by emitting a burst of high frequency sound and listening for the echo from the seafloor. Sound is emitted from a source on the ship and the returning echo is detected by a receiver on the ship. Deeper water means longer time for the echo to return to the receiver

Answer 10

Echo sounding

Question 11

profiles the shape of the sea surface by measuring the travel time of a radar pulse from the satellite to the ocean surface and back to the satellite receiver. The shape of the sea surface approximates the shape of the sea floor

Answer 11

Satellite altimetry

Question 12

submerged outer edge of the continent where continental crust transitions into oceanic crust

Answer 12

Continental margin

Question 13

features a wide, gently sloping continental shelf (50-200m depth), a steeper continental slope (3000-4000m depth), and a flatter continental rise

Answer 13

Passive or Atlantic type

Question 14

characterized by a narrow shelf and slope that descends into a trench or trough

Answer 14

Active or Pacific type

Question 15

abyssal plain is an extremely flat, sediment-covered stretches of the ocean floor, interrupted by occasional volcanoes, mostly extinct, called seamounts

Answer 15

Abyssal plains and abyssal hills

Question 16

a submarine mountain chain that winds for more than 65,000 km around the globe. It has a central rift valley and rugged topography on its flanks

Answer 16

Mid- Ocean ridges

Question 17

narrow, elongated depressions on the seafloor many of which are adjacent to arcs of island with active volcanoes; deepest features of the seafloor

Answer 17

Deep-ocean trenches

Question 18

submerged volcanoes are called seamounts while those that rise above the ocean surface are called volcanic islands. These features may be isolated or found in clusters or chains.

Answer 18

Seamounts and volcanic islands

Question 19

are the edges where two plates meet

Answer 19

Plate boundaries

Question 20

read abt the wilson cycle

Answer 20

yup