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