| A | B |
|---|
| fossil | trace or remains of once living organisms |
| trace | type of fossil formed by a footprint or poo poo found in sedimentary rock |
| mold | type of fossil that is formed by the impression left in rock by the remains of an organism |
| cast | type of fossil that occurs when the mold is filled in by precipitating minerals |
| uniformitarianism | geologic processes in the past can be explained by current geologic processes |
| amber | fossilized tree resin (not sap) |
| sediment | matter that settles to the bottom of a liquid |
| petrified | to become stiff or stone like |
| extinction | the end of an organism or of a group of organisms (taxon), normally a species |
| species | a group of organisms capable of interbreeding and producing fertile offspring |
| radiometric_dating | a technique used to date materials such as rocks, usually based on a comparison between the observed abundance of a naturally occurring radioactive isotope and its decay products |
| relative_dating | Relative dating is the science determining the relative order of past events, without necessarily determining their absolute age |
| superposition | sedimentary layers are deposited in a time sequence, with the oldest on the bottom and the youngest on the top |
| unconformity | break in geologic record when rock layers are eroded |
| geologic_column | ordered arrangement of rock layers with oldest at the bottom and the youngest at the top |
