___________________ continues to cause areas like North America and Africa to move farther apart.
Earthquake shaking
Island slide
Continental drift
The Pacific Ocean
Rivers often serve as natural __________, separating one piece of land from another.
bridges
boundaries
walls
gates
All of Earth’s continents were once joined together in one large ___________.
plate
island
ocean
landmass
Many people were amazed when Jake's ____________ about the future became true.
guesses
plans
predictions
ideas
Running is one activity that requires a lot of ________.
power
energy
practice
strength
Many American _______________ have trails that allow hikers to climb across several mountains.
valleys
foothills
mountain ranges
canyons
A major ______________ runs through California, which is why they have a lot of big earthquakes.
crack
plate
glacier
fault line
Lava, or ________ rock, often flows out of a volcano during an eruption.
moist
frozen
molten
dessicated
An understanding of ________________ has helped explain how and why earthquakes occur.
oceans
meteorology
plate tectonics
history
The Earth's ________ is a rocky shell that measures about 2,900 kilometers thick.
layer
crust
mantle
core