Bech Spring Dolomite (image) Arizona State University Share Print E-Mail Caption This is a late Precambrian carbonate outcropping at south end of Death Valley, California. Carbon isotopes in these layers bear evidence of the first extensive greening of the Earth. Credit L.P. Knauth, Arizona State University Usage Restrictions None Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.