| Question |
Answer |
| fossil |
the preserved remains or traces of an organism |
| petrified fossil |
a fossil formed when minerals replace all or part of an organism |
| carbon film |
plant leaves may form this fossil by leaving a thin layer of carbon on rock |
| trace fossils |
a type of fossil that can provide clues about the activities of ancient organisms |
| paleontologist |
scientist who studies fossils |
| extinct |
a type of organism that no longer exists on Earth |
| relative age of a rock |
its age compared to the ages of other rocks |
| Law of Superposition |
in horizontal layers of sedimentary rock, each layer is older than the layer above it and younger than the layer below it |
| unconformity |
a gap in the geologic record where some rock layers have been lost because of erosion |
| index fossils |
the fossils of organisms that were widely distributed but only lived during a short period of time |
| radioactive decay |
occurs when atoms of an unstable element break down to form atoms of another element |
| half-life |
the time it takes for half of the radioactive atoms in a sample of a radioactive element to decay |
| geologic time scale |
a record of the life forms and geologic evewnts in Earth's history |
| vertebrates |
animals with backbones |
| Pangaea |
a supercontinent formed about 260 million years ago |
| fossil in amber |
a type of fossil where you might find the remains of an insect preserved with little or no change |
| evolution |
the process by which all the different kinds of living things have changed over long periods of time |
| absolute age of rocks |
can be determined by radioactive dating |
| eras |
the divisions of the geologic time scale of Paleozoic, Mesozoic, and Cenozoic |
| Cenozoic Era |
Age of Mammals includes present day |
| Mesozoic Era |
Age of Reptiles includes the dinosaurs |
| mammals |
warm-blooded vertebrates |
| Quarternary Period |
a series of ice ages occurred when Earth's climate cooled |
| carbon-14 |
a radioactive element used by geologists to determine the age of organic remains |
| age of Earth |
4.6 billion years old |
| igneous rocks |
rocks that radioactive dating works best with |
| amphibian |
an animal that lives part of its life on land and part of its life in water |
| Precambrian Time |
began with Earth forming from a mass of dust and gas |
| fossils form |
when living things die adn their remains are buried by sediments |
Science Vocab 147928
