This is an irregular verb and the conjugations need to be memorized. A short lesson explains how. Mentir - French Verb Conjugations Learn how to conjugate mentir, an irregular -ir French verb. This is not an easy verb to conjugate, so you will need a good lesson to show you how.
Metamorphism occurs because some minerals are stable only under certain conditions of pressure and temperature. When pressure and temperature change, chemical reactions occur to cause the minerals in the rock to change to an assemblage that is stable at the new pressure and temperature conditions.
This friction generates enough heat to melt the rocks at the point of contact. Heat For metamorphism to occur energy is needed to fuel the chemical reactions. Heat is the primary source of this energy.