Plate Tectonics- Part I & II
Wegener’s ____________________________hypothesis stated that the continents had once
been joined to form a single supercontinent-_________________, began to break apart 200
million years ago and form the present landmasses.
Evidence of Continental Drift:




Seafloor Spreading
 “Stripes” on the seafloor indicated periods of reversed ______________
 Provided ___________________ to support Wegener’s Continental Drift hypothesis
Mechanisms responsible for seafloor spreading are slab pull and mantle convection. Hotter
mantle material rises beneath __________________ boundaries, cooler material sinks at
______________ ___________.
Earth’s surface consists of a number of rigid, but moving __________ that ___________.
Theory of Plate Tectonics:______________________________________________________
____________________________________________________________________________
Evidence of Plate Tectonics:

__________________________: rocks formed millions of years ago show the
location of the magnetic poles at the time of their formation.

lithosphere:__________________________________________________________________
- made of __________________ and ______________________
- rigid plates that ________________________________________
- “Floats” on the ______________________
asthenosphere:_______________________________________________________________
types of Earth’s crust:
-oceanic crust:_____________________________________________________
-continental crust:__________________________________________________
where convention currents are rising, ________________________________________
______________________________________________________________________
______________________________________________________________________
where cooler, denser currents are sinking, ____________________________________
______________________________________________________________________
plate boundaries:_____________________________________________________________
belts where _______________________ and ________________________ are
located- _______________________________________________________________
when stress is too great- __________________________________________________
boundaries are also area of high heat flow, ___________________________________
______________________________________________________________________
Kinds of Plate Boundaries
1) divergent boundaries:_____________________________________________________
____________________________________________________________
contain _______________________________ which have deep valleys along entire
length called ________________________________
as plates move apart, ____________________________________________________
_____________________________________________________(seafloor spreading)

When spreading centers develop within a continent, the landmass may split into two
or more smaller segments, forming a ____________________________________.
2) converging boundaries:____________________________________________________
there are 3 types
-subduction zone:__________________________________________________
-ocean plate__________________________________________________
-forms_______________________________________________________
-continent to continent convergence (collision): ________________________
________________________________________________________________
-become ___________________________________________
-form______________________________________________
- oceanic to oceanic convergence: ________________________________
_______________________________________________________________
_______________________________________________________________
-form _______________________________________________________
3) transform fault boundaries:_________________________________________________
____________________________________________________________________________
transform fault:_________________________________________________________
______________________________________________________________________
-example:________________________________________
 Factors that influence the strength of a rock and how it will deform include:_____________,
_________________, _____________________________, and _____________________
fault: _______________________________________________________________________
caused by _______________________________
faulted rocks have two blocks:
-hanging wall: ______________________________________________________
-foot wall: _________________________________________________________

___________________: formed when hanging
wall moves down relative to the foot wall

___________________: formed when hanging wall
moves up relative to the foot wall

___________________: rocks on either side of
fault are moving past each other
fold: _______________________________________________________________________
-anticlines:_________________________________________
forms_______________________________________
-synclines:_________________________________________
forms_______________________________________