Gneiss is a type of rock that is formed from other rocks through intense heat and pressure. It has distinct layers or bands, making it look striped or banded. Full definition
«The oldest rocks in the Koongarra area, domes of granitoids and granitic gneiss, are of Archaean age (ie to geologists this means they are older than 2500 million years). (religion.blogs.cnn.com)