formation of Precambrian rocks (dating from 3.96 billion to 540 million years ago) in the region of Adelaide, South Australia. The Pound Quartzite consists of shales and siltstones, limestones, and quartzites; it is notable because from it a very early fossil assemblage, the Ediacara fauna, was recovered. The fossil assemblage evidences a variety of types, many of which are surprisingly complex and afford a rare glimpse at the diversity of Precambrian animal life.