Archæan

(är-kē´an) Rocks (Gr. archaios , ancient), the oldest rocks of the earth's crust, 220 mostly crystalline in character, and embracing granites, gnei es, mica-schists, ., all devoid of fo il remains. These rocks underlie a group of stratified and igneous ma es that are usually distinguished from them as Huronian; the first beds with a well-marked fauna (lowest Cam brian) lie above the Huronian, and the Huronian and the Archæan groups are often conveniently cla ed together as pre-Cam brian, and are separated from the stratified and fo iliferous formations, which indeed have chiefly taken origin from them. The core of the Malvern range, and the rocks of N.W. Sutherland, are examples of Archæan ma es in Great Britain.