Referring to the arizona geologic map: what is the symbol for the oldest rocks on the map?

The first atomic explosion was detonated in the desert north of alamogordo, new mexico, on july 16, 1945. what percentage of the strontium-90 ( yr) originally produced by that explosion still remains as of july 16, 2016?

This desert is found in the northern part of africa and covers 3.5 million square miles.

An igneous rock that contains mostly pyroxene and olivine has what type of composistion