Digital Bedrock Geologic-GIS Map of the Twin Bridges Quadrangle, Tennessee (NPS, GRD, GRI, OBED, TWBR_bedrock digital map) adapted from a Tennessee Division of Geology Geologic Quadrangle Map by Coker (1965)

The Digital Bedrock Geologic-GIS Map of the Twin Bridges Quadrangle, Tennessee is composed of GIS data layers and GIS tables, and is available in the following GRI-...田纳西州双子桥图幅数字基岩地质地理信息系统（Geographic Information System，简称GIS）图由GIS数据图层与GIS数据表构成，可通过下述GRI-……获取。