Focus On Earth Science: California Grade 6

Lesson 2: Seafloor Spreading

Standards Check

1.
Which was not evidence presented by Alfred Wegener to support his hypothesis of continental drift? 1.a
A)reversals of Earth's magnetic polarity
B)the distribution of certain fossils
C)the geographic fit of the continents
D)locations of mountain ranges and rock types
2.
Where does seafloor spreading occur? 1.c
A)in the middle of oceanic plates
B)at ocean trenches
C)at Spitzbergen
D)at mid-ocean ridges
3.
What type of rock is found in oceanic crust? 1.c
A)granite
B)basalt
C)gneiss
D)peridotite
4.
Oceanic plates are usually much _______ than continental plates. 1.b
A)thicker
B)heavier
C)thinner
D)lighter
5.
The decay of radioactive elements in Earth's interior produces _______. 1.b
A)continental crust
B)magnetic reversals
C)heat
D)oceanic crust
Grade 6
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