Preliminary geologic map emphasizing bedrock formations in Contra Costa County, California: A digital database

This digital map database, which is compiled from previously published and unpublished sources combined with new mapping, represents the general distribution and identity of bedrock in Contra Costa County, California.本数字地图数据库整合既往已发表与未发表的资料，并结合新测绘工作编纂而成，完整呈现了美国加利福尼亚州康特拉科斯塔县（Contra Costa County）内基岩的总体分布与属性特征。