The earth is divided like a puzzle a series of compartments called rigid lithospheric plates.

core-wietcher-lehmen        continental drift-Arthur-Wegner

Paleomagnetism

-Age of the seaved

-conclussion: 1)The earth's magnetic field has inverted his polarity many times throught the planet's history.

                    2) The only explanation for the symmetrical distribution of the paleomagnetic bands was that the seabed must have expanded fon the axis                              of the ridge.

-In the seabed there is ridges and volcanos

-In the middle of the ocean there are volcanos that erupt new material produced in the mantle, this produce the expansion to the sides at the old ocean crust.                                                                                              

-Generates:continuous renovation of ocean crust.        

-The most importat geological activity is concentrated in ridges and trinches.

Plate tectonics

-Global theory - explains all the geological process

Proposals:1) Lithosphere divided into rigid fragments called tectonic plates.

                 2)Lithospheric places are dynamic(move increase and decrease in size and change shape)

                  3) Plated interact, especially at their boundaries or limits

                   4)Dynamics of the lithosperic plates can explain all the gelogical processes

Boundaries: it is a limit

1)Divergents or constructiveIt<------  ------> generates: ridges,volcanos and earthquake

2)Convergent/Destructive------><-------  generates: trenchs,a lot seismic activity,volcanism

SUBDUCTION: when a plate sink into another one.