Examining the crust
There is a layer called the asthenosphere by which the tectonic plates move upon - they move about 2-5 cm a year. These tectonic plates make up the lithosphere.
There are two type of crust. There is continental crust which forms the land. This continental crust is made up mostly of granite (low density igneous rock). Then, there is the crust under the oceans called the oceanic crust. This is much denser and is made of igneous rock called basalt.
The asthenosphere and mantle
If the asthenosphere was a liquid, the tectonic plates would sink so it is though that the…