Show:
Earth
Universe
Earthquakes/Volcanoes
Water
Riddles
100
The Earth's natural satellite.
Moon
100
The name of our galaxy.
Milky Way
100
Area of great volcanic activity.
Ring of Fire
100
Universal solvent
Water
100
It occurs once every minute, twice any moment, but never in a year.
M
200
The middle zone of Earth.
Mantle
200
Planet closest to the sun.
Mercury
200
The largest volcanoes on Earth.
Caldera
200

The area that cannot take up any more water.

Saturated zone
200
I'm tall when I'm young and short when I'm old.
Candle
300
Deepest trench in the world. 
Mariana Trench
300
Planet farthest away from the sun. 
Neptune
300
The resistance to pouring or its 'thickness'.
Viscosity
300
When plants sweat.
Transpiration
300

Runs around a house but does not move.

Fence
400

Sediments, soil, and rocks are added to a landform or land mass.


Deposition
400
The first atom. 
Hydrogen
400
Molten rock beneath the surface.
Magma
400
Name of an important aquifer in the Midwest. 
Ogallala
400

Has a bed but doesn’t sleep and a mouth but never eats.

River
500

Light, less dense, and warm material rises while heavy, more dense, and cool material sinks.

Convection current
500
The person who classified galaxies.  
Edwin Hubble
500
The boundary where crust is pulled apart. 
Divergent
500

Phosphate and nitrate levels are too high.

Eutrophication
500

Flies without wings and cries without eyes. 

Cloud