| Before the use of mass spectrometry in isotopic geochronology, helium dating provided most of the dates used in the early geologic time scales. |
| In fact, just the opposite was true they found that eyes could evolve rapidly in geologic time scales. |
| Reaction rates depend on temperature, pH, and HCN, NH3, and aldehyde concentrations but are rapid on geologic time scales. |
| There are, in fact, two geologic time scales. |
| River incision into bedrock drives the topographic evolution of mountainous terrain and may link climate, tectonics, and topography over geologic time scales. |
| All lakes are temporary over geologic time scales, as they will slowly fill in with sediments or spill out of the basin containing them. |
