Marble is a metamorphic rock that forms when limestone or dolostone is exposed to high heat and pressure without undergoing melting. The heat and pressure causes the molecules (primarily calcite) to...
According to Answers.com, Reference Answers prong in geology is a prong reef described a wall reef that has developed irregular buttresses normal to its axis in both leeward and (to a smaller degree)...
It means years x 10 to the power of 9.
It is the unit that the age of of the earth is measured in.
It stands for Giga Anum
Giga = 10^9 and Anum = 1 year