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