PLEASE HURRY
One of the big ideas of continental drift theory states that all of the continents used to ___________________________.
a have a continuous layer of dense glacial ice
b form a single, massive continent called Pangea
c constantly change as global volcanic chains erupted
d be broken into millions of small, distinct archipelagos
Magnetic patterns in the igneous bedrock on the ocean floor _________________________________________________.
a indicate that all ocean rocks have reversed polarity
b differ greatly from the patterns found in rocks on land
c show alternating bands of normal and reversed polarity
d seems to be unrelated to the age of the bedrock
Plates that are subducted at convergent boundaries can form _______________________________________.
a rolling hills
b deep-sea trenches
c rift valleys
d tall, folded mountains
Oceanic trenches are long, narrow depressions on the ocean floor. An oceanic trench is formed when one plate ____________________________________________________________.
a dips below another plate
b pulls back from another plate
c splits into two plates
d grinds against another plate