This 1:24,000-scale geologic map of the Lamar 7.5-minute quadrangle shows the distribution of unconsolidated to semiconsolidated Holocene and Pleistocene geologic units deposited on the Texas coastal plain in fluvial, deltaic, bay, estuarine, lagoonal, and Gulf-margin environments. The GeMS GIS database contains mapped lines and polygons representing geologic features, contacts, and geologic units. The database conforms to GeMS (Geologic Map Schema)--a standard format for the digital publication of geologic maps developed by the U.S. Geological Survey National Cooperative Geologic Mapping Program.