Answer:
As per the question, scientists find a dense rock on earth's surface that is made of Mg and smaller amounts of Al and silicon is found in Mantle beneath the earth's surface.
Step-by-step explanation:
- As the structural composition of the earth is made up of primarily three layers i.e earth crust, core and mantel being the second layer found just below the surface of the earth is primarily and mostly composed of Aluminum and rocks that have silicon in them.
- So the layer that is below this is made of desert rock matter hence it's composed of Mg and iron and other elements.
- The study of this layer of the earth helped the scientists to identify the various types and patterns of tectonic movements inside the earth and also as this layer is responsible for the free flow of lava and magma flows at greater depths.