| A | B |
|---|
| plates | the sections Earth's lithosphere is broken into |
| geologists | scientists who study the forces that make and shape the earth |
| molten material | the stuff that eupts through the valley of the mid-ocean ridge |
| mid-ocean ridge | the place where molten material rises from the mantle and erupts |
| sonar | the technology that scientists used in the mid-1900s to map the mid ocean ridge |
| density | the measure of how muchmass there is in a volume of a substance |
| lithosphere | all of the crust and part of the mantle |
| intrusive | igneous rock that forms from magma |
