Lithosphere Lithosphere: The lithosphere comprises the Earth’s crust as well as part of the upper mantle. In fact, the lithosphere is approximately 100 kilometers thick and is relatively strong as compared to the underlying asthenosphere.

Mafic Definition In geology, “mafic” is a term that describes an igneous rock that has an abundance of darker color minerals.

Facies Facies: In the field of geology, the term “facies” represents a mappable, areally restricted part of a rock body that has different fossils or lithology from other contiguous beds deposited at the same time.

Twinning Definition Twinning is the observed intergrowth of multiple crystals in a symmetrical fashion. This term applies to the examination of rock thin sections, in the field of optical mineralogy.