Quantitative bedrock geology of the conterminous United States of America
Additional Document Info
 We quantitatively analyze the area-age distribution of bedrock based on data from the most recent geologic map of the conterminous United States of America [King and Beikman, 1974a, 1974b], made available in digital form by the United States Geologic Survey. The area-age distribution agrees surprisingly well with older data [Higgs, 1949] but provides much higher temporal resolution. The mean stratigraphic age of all sedimentary bedrock is similar to134 Myr; that of Tertiary-Cambrian sediments is similar to104 Myr. The analysis also reveals area coverage of some minor lithologies, such as ultramafic rocks that cover similar to0.15% of the conterminous United States. Area coverage of 162 lithostratigraphic units is made available as an Excel data sheet.