Western US Rock Types Middle Proterozoic gneiss Middle Proterozoic gneiss Middle Proterozoic gneiss Middle Proterozoic gneiss Cretaceous sedimentary rocks Cretaceous sedimentary rocks Cretaceous sedimentary rocks Cretaceous sedimentary rocks Cretaceous sedimentary rocks Cretaceous sedimentary rocks Cretaceous sedimentary rocks Cretaceous sedimentary rocks Cretaceous sedimentary rocks Cretaceous sedimentary rocks Cretaceous sedimentary rocks Cretaceous sedimentary rocks Cretaceous sedimentary rocks Cretaceous sedimentary rocks Cretaceous sedimentary rocks Paleogene sedimentary rocks Paleogene sedimentary rocks Mesozoic granitic rocks Mesozoic sedimentary rocks Mesozoic granitic rocks Paleozoic sedimentary rocks Paleogene granitic rocks Cretaceous sedimentary rocks Gneiss, age uncertain Quaternary deposits Paleogene volcanic rocks Paleogene sedimentary rocks Neogene volcanic rocks Paleogene sedimentary rocks Quaternary deposits Neogene volcanic rocks Neogene volcanic rocks Neogene volcanic rocks Neogene volcanic rocks Neogene volcanic rocks Neogene volcanic rocks Neogene volcanic rocks Neogene volcanic rocks Neogene volcanic rocks Neogene volcanic rocks Neogene volcanic rocks Neogene volcanic rocks Quaternary deposits Middle Proterozoic gneiss Paleogene volcanic rocks Middle Paleozoic (Silurian, Devonian, and Mississippian) sedimentary rocks Middle Paleozoic (Silurian, Devonian, and Mississippian) sedimentary rocks Cretaceous granitic rocks Quaternary deposits Paleozoic sedimentary rocks Paleogene sedimentary rocks Quaternary deposits Cretaceous granitic rocks Paleogene sedimentary rocks Paleogene volcanic rocks Archean gneiss Archean gneiss Cretaceous granitic rocks Middle Proterozoic gneiss Middle Proterozoic sedimentary rocks Quaternary deposits Paleozoic sedimentary rocks Paleozoic sedimentary rocks Paleozoic sedimentary rocks Mesozoic sedimentary rocks Archean gneiss Quaternary volcanic rocks Paleogene sedimentary rocks Quaternary volcanic rocks Paleogene sedimentary rocks Paleogene sedimentary rocks Paleogene sedimentary rocks Paleozoic and Mesozoic sedimentary rocks Paleozoic and Mesozoic sedimentary rocks Paleogene volcanic rocks Paleogene volcanic rocks Lower Mesozoic (Triassic and Jurassic) sedimentary rocks Lower Mesozoic (Triassic and Jurassic) sedimentary rocks Middle Paleozoic (Silurian, Devonian, and Mississippian) sedimentary rocks Neogene sedimentary rocks Mesozoic sedimentary rocks Paleozoic sedimentary rocks Neogene sedimentary rocks Cretaceous sedimentary rocks Neogene volcanic rocks Paleozoic sedimentary rocks Quaternary deposits Quaternary deposits Mesozoic sedimentary rocks Paleogene sedimentary rocks Paleogene sedimentary rocks Paleogene sedimentary rocks Neogene sedimentary rocks Neogene sedimentary rocks Neogene sedimentary rocks Neogene sedimentary rocks Paleozoic sedimentary rocks Mesozoic sedimentary rocks Mesozoic sedimentary rocks Mesozoic sedimentary rocks Mesozoic sedimentary rocks Paleozoic sedimentary rocks Lower Mesozoic (Triassic and Jurassic) sedimentary rocks Neogene sedimentary rocks Mesozoic sedimentary rocks Mesozoic sedimentary rocks Paleogene sedimentary rocks Paleogene sedimentary rocks Quaternary deposits Paleozoic and Mesozoic sedimentary rocks Neogene sedimentary rocks Neogene sedimentary rocks Quaternary volcanic rocks Neogene sedimentary rocks Paleozoic sedimentary rocks Water body Water body Water body Paleozoic sedimentary rocks Paleozoic sedimentary rocks Paleozoic sedimentary rocks Quaternary deposits Quaternary deposits Paleogene sedimentary rocks Quaternary deposits Proterozoic sedimentary rocks Cretaceous sedimentary rocks Cretaceous sedimentary rocks Lower Mesozoic (Triassic and Jurassic) sedimentary rocks Paleozoic sedimentary rocks Paleogene sedimentary rocks Cretaceous sedimentary rocks Paleozoic sedimentary rocks Neogene sedimentary rocks Quaternary deposits Paleogene volcanic rocks Paleogene volcanic rocks Paleogene sedimentary rocks Cretaceous and Tertiary sedimentary rocks Neogene volcanic rocks Paleogene volcanic rocks Paleogene volcanic rocks Paleogene volcanic rocks Neogene volcanic rocks Paleogene sedimentary rocks Paleozoic sedimentary rocks Upper Paleozoic (Pennsylvanian and Permian) sedimentary rocks Early Proterozoic gneiss Lower Mesozoic (Triassic and Jurassic) sedimentary rocks Lower Mesozoic (Triassic and Jurassic) sedimentary rocks Lower Mesozoic (Triassic and Jurassic) sedimentary rocks Quaternary deposits Quaternary deposits Quaternary deposits Paleozoic sedimentary rocks Cretaceous sedimentary rocks Quaternary deposits Middle Proterozoic granitic rocks Lower Mesozoic (Triassic and Jurassic) sedimentary rocks Lower Mesozoic (Triassic and Jurassic) sedimentary rocks Lower Mesozoic (Triassic and Jurassic) sedimentary rocks Lower Mesozoic (Triassic and Jurassic) sedimentary rocks Lower Mesozoic (Triassic and Jurassic) sedimentary rocks Proterozoic granitic rocks Proterozoic granitic rocks Proterozoic granitic rocks Neogene sedimentary rocks Neogene volcanic rocks Cretaceous granitic rocks Quaternary deposits Paleogene volcanic rocks Mesozoic sedimentary rocks Paleogene volcanic rocks Quaternary deposits Upper Paleozoic (Pennsylvanian and Permian) sedimentary rocks Quaternary deposits Cretaceous sedimentary rocks Paleogene sedimentary rocks Mesozoic sedimentary rocks Mesozoic sedimentary rocks Neogene volcanic rocks Paleozoic and Mesozoic sedimentary rocks Neogene volcanic rocks Paleogene sedimentary rocks Upper Paleozoic (Pennsylvanian and Permian) sedimentary rocks Upper Paleozoic (Pennsylvanian and Permian) sedimentary rocks Neogene volcanic rocks Neogene volcanic rocks Upper Paleozoic (Pennsylvanian and Permian) sedimentary rocks Neogene sedimentary rocks Quaternary deposits Cretaceous sedimentary rocks Cretaceous sedimentary rocks Neogene sedimentary rocks Upper Paleozoic (Pennsylvanian and Permian) sedimentary rocks Upper Paleozoic (Pennsylvanian and Permian) sedimentary rocks Upper Paleozoic (Pennsylvanian and Permian) sedimentary rocks Lower Mesozoic (Triassic and Jurassic) sedimentary rocks Neogene volcanic rocks Neogene volcanic rocks Paleozoic sedimentary rocks Neogene volcanic rocks Early Proterozoic granitic rocks Cretaceous granitic rocks Neogene volcanic rocks Neogene sedimentary rocks Quaternary deposits Quaternary deposits Mesozoic granitic rocks Quaternary deposits Quaternary deposits Quaternary deposits Quaternary deposits Quaternary deposits Quaternary deposits Lower Mesozoic (Triassic and Jurassic) sedimentary rocks Paleogene sedimentary rocks Upper Paleozoic (Pennsylvanian and Permian) sedimentary rocks Early Proterozoic gneiss Early Proterozoic granitic rocks Quaternary deposits Quaternary deposits Paleogene sedimentary rocks Quaternary volcanic rocks Paleogene volcanic rocks Quaternary deposits Quaternary deposits Middle Proterozoic sedimentary rocks Cretaceous granitic rocks Cretaceous granitic rocks Paleogene volcanic rocks Paleogene sedimentary rocks Neogene sedimentary rocks Quaternary deposits Neogene sedimentary rocks Paleogene volcanic rocks Quaternary deposits Quaternary deposits Quaternary deposits Quaternary deposits Cretaceous sedimentary rocks Cretaceous sedimentary rocks