Alfred Wegener wrote his book, The
Origin of Continents and Oceans, in 1912,
First proposed his hypothesis in 1915.
Henry Hess
Harry Hess was a geologist. During World
War II, he was also commander of naval
submarines. The task was to study the
deepest part of the seabed. He proposed in
1960 that continental movement is the
result of submarine proliferation. Molten
magma from below the crust may overflow
between the plates and the rift valley. Hess
cruised and clarified the broken continents
that were once connected. These are the
seven continents we are familiar with. But
the plates move and change shape.
Plate tectonics
the lithosphere of the earth is divided into a
small number of plates which float on and travel
independently over the mantle and much of the
earth's seismic activity occurs at the boundaries
of these plates
Sea floor spreading
Seafloor Spreading: We need
evidence. The first evidence is
the ocean floor. There are active
fractures in the lithosphere
around the ocean floor, In a
pattern that mimics the shape of
the continental coastline. The
age of the sea floor Rock
increases as you get further
away from the mid-ocean ridge.
The thickness of the layer of
sediments and the ocean floor
increases as you get further
away from the mid-ocean ridge.