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