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