| Qs: Sediments |
| Ql: Shallow-lake sediments |
| Qld: Deep-lake sediments |
| Qhe: Hydrothermal-explosion deposits |
| Qh: Hydrothermal deposits |
| Qls: Landslide deposits |
| Qt: Talus and slope deposits |
| Qg: Glacial deposits |
| Qg(?): Glacial(?) deposits |
| Qpcu: Spruce Creek rhyolite flow |
| Qpce: Elephant Back rhyolite flow |
| Qpcw: West Thumb rhyolite flow |
| Qpca: Aster Creek rhyolite flow |
| Qpci: Tuff of Bluff Point |
| Qpcd: Dry Creek rhyolite flow |
| Qpcpv: Pelican Creek rhyolite flow |
| Qyl: Lava Creek tuff |
| QTplc: Pre-Lava Creek Yellowstone Group rhyolites, undifferentiated |
| Tv: Tertiary volcanic rocks, undifferentiated |
| pE: Pre-Eocene rocks, undifferentiated |
| water |