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