EXPLANATION OF COLORS ON USGS MAP I-1970


Colors indicate different types of sediment at land surface:
  • GREEN = till
  • YELLOW TO RED = coarse, stratified sediment
  • BLUE = fine, stratified sediment
Color intensity indicates total thickness of Quaternary sediment:
  • Pale colors = thin sediment
  • Dark colors = thick sediment

NOTE: This diagram shows only the three most common sediment types. A full description of map units is found on the printed map and in the metadata.