Chapter 12, Problem 1GST

To determine

The reasons for the increase of density in Earth’s interior with depth.

Answer to Problem 1GST

The mineral phase change and compression of prevailing minerals by intense pressure are the major reasons for the increase in the density of Earth’s interior with depth.

Explanation of Solution

The overlying rocks exert a great amount of pressure on the underlying layers and composing rocks. Thus the mantle and core which are located deep inside Earth under high pressure. This causes the rocks to become even tighter and compacted.

Due to the high pressure, the minerals of the inner layers such as olivine and pyroxene in the ultramafic rock peridotite becomes unstable and thus alters to a stable-structured form through the mineral phase change. The atoms of the minerals that undergo phase change get compressed, shrunk and occupy in a very less volume. Hence the volume decreases while the number of atoms accommodated in the space increases. Thus the resultant minerals and rocks would be denser and compact.