Last time, we discussed a broad overview of
the Earth’s Mantle.
In the Upper Mantle, there are two distinct
regions called the lithosphere and asthenosphere.
The lithosphere is the solid, outer part of
our planet.
It is composed of the rigid upper portion
of the mantle as well as the crust, which
is the outermost layer of the Earth.
There are two types of lithosphere, the continental
and oceanic lithosphere which are part of
the Earth’s crust.
The asthenosphere is the denser, weaker, and
semi-molten region beneath the lithospheric
mantle.
This region is where rocks soften and partly
melt, giving this area a thick, sticky consistency.
The lithosphere-asthenosphere boundary or
LAB is the point of transition from the solid
lithosphere into the more “gooey” asthenosphere.
The LAB’s depth changes from place to place.
The lithosphere is divided into huge slabs
called tectonic plates.
This region is known for its association with
tectonic activity.
The tectonic plates slowly move on top of
the melted rock beneath them in the asthenosphere.
When these plates interact with each other
they cause geologic activity such as earthquakes
or volcanic eruptions.
Later on we’ll explore more about plate
tectonics.
Next time, we’ll look into the characteristics
of the crust.
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