Unit 4 Lesson 2 Plate Tectonics Notes (pgs. 200-213)
1.______________________________________________ - Alfred Wegener’s hypothesis that the continents once
formed a single land mass which broke up and drifted apart.
2. EVIDENCE TO SUPPORT CONTINENTAL DRIFT
Shape of the Land
Mesosaurus Fossil
(cute little reptile)
___________________ and
Fossils found on
_________________ ____
___________________ and
______________________
fit together like puzzle
pieces.
_____________________
Glossopteris Fossil
(Fern-like plant)
Mountains
Found on ______________
land masses
North _________________
Seeds could not have blown
across the seas because
they were too
and __________________
mountains are the same
age and same composition
and line up If the continents
were together.
______________________.
3.______________________________ - the single large landmass that existed 245 million years ago
4. Continental drift was not accepted because Wegener could not ____________________________________________
__________________________________________________________________________________________________
5. In the mid-1900s scientists used new technology (sonar) to map the ocean floor and discovered __________________
ridges. These ridges formed along cracks in the crust on the ocean floor.
6. This brought about a new proposal called __________________________________________ spreading. In this
process, ____________________________ from inside Earth ________________ through the ________________ in the
mid-ocean ridges, ______________________, and forms __________________ ocean crust.
7. EVIDENCE TO SUPPORT SEA-FLOOR SPREADING
Age of rock on the ocean
floor
Magnetic patterns on the
ocean floor
Ocean trenches on the
ocean floor
8. _______________________________________________ - a theory that pieces of Earth’s lithosphere are in constant
motion, driven by convection currents in the mantle (This is a different definition that in the Dynamic Earth book.)
9. _______________________________________________ - pieces of the lithosphere which move around on top of the
asthenosphere in different directions at different speeds. Some plates are made of just ocean, or just continent or both.
11. _________________________ plates are much more dense than ________________________ plates.
12. Continental plates are underlain by the rock ________________ and oceanic plates by the rock ________________.
13. Basalt is a much more dense rock than granite.
14. There are _____________ types of plate boundaries.
CONVERGENT BOUNDARY
DIVERGERNT BOUNDARY
TRANSFORM BOUNDARY
15. Tectonic plates move due to differences in density and which is called ____________________________.
16. As the mantle convects, or moves, it _________________ the overlying __________________ plates along with it.