click below
click below
Normal Size Small Size show me how
Our Changing Earth U
8th Grade Our Changing Earth Unit
Word | Definition |
---|---|
Adaptation | A trait that increases the chances that an organism will survive and reproduce |
Artificial Selection | The breeding of plants and animals with desired traits to attempt to produce offspring with these same traits |
Biological Evolution | The change over time of living organisms |
Darwin | A naturalist who proposed and provided scientific evidence that all species of life have ecolced over time from common ancestors through the process he called natural selection |
Evolution | The change in population of a species over time |
Extinction | The evolutionary termination of a species caused by the failure to reproduce and the death of all remaining members of the species; the natural failure to adapt to environmental change |
Fossil | evidence of past life preserved in rock |
Fossil Record | The complete body of fossils that shows how species and ecosystems change over time |
Fossilized | The process of becoming a fossil |
Index Fossil | A fossil found in a narrow time range but widely distributed around the earth; used to date rock layers |
Mutation | A random change to a gene that results in a new trait |
Natural Selection | Survival of the fittest organisms that the best adapted to their environment and the ones that will live long enough to reproduce and pass on their favorable adaptations |
Species | The most specific classification of living things |
Speciation | the process of natural selection producing a new species out of existing species of thousands or millions of years |
Theory | An explanation that ties together many hypothesis and observations |
Trace Fossil | A fossilized mark that is formed in soft sediment by the movement or actions of an animal |
Trilobite | A marine organism that is an example of an index fossil |
Absolute Dating | Any method of measuring the age of an event or object in years. The actual age for a rock or mineral |
Continental Drift Theory | Theory that states that the gradual shifting of Earth's plates causes continents to change their global positions over time |
Correlation | The matching up of rock layers from different locations |
Convergent plate boundary | The boundary formed by the collision of two lithospheric plates |
Daughter Isotope | The stable isotope that results from radioactive decay |
Divergent plate boundary | The boundary between two tectonic plates that are moving away from each other |
Half-Life | The time needed for half of a sample of radioactive substance to undergo radioactive decay |
Isotope | An atom that has the same number of protons as other atoms of the same element do but that has a different number of neutrons |
Law of Superposition | States that the oldest rocks lie on the bottom and the youngest rocks are on the top of any undisturbed sequence of sedimentary rocks |
Parent Isotope | An atomic nucleus that undergoing decay |
Plate Tectonics | The theory that explains how large pieces of the Earth’s outermost later called tectonic plates move and change shape |
Radioactive Dating | The process by which the age of a rock is determined by measuring the among of radioactive isotopes present in the rock or rock sample |
Radiometric Dating | The method used for absolute dating |
Radioactive Decay | The process in which a radioactive isotope tends to break down into a stable isotope of the same element or another element |
Relative Dating | Uses info about rock layers and the fossil record to determine the age relationships between rocks |
Unconformity | Gaps in the rock record |
Eon | The largest division of geologic time |
Epoch | A subdivision of a geologic period |
Era | A unit of geologic time that includes two or more periods |
Geologic Time Scale | The standard method used to divide the Earth’s long natural history into manageable parts |
Cenozoic Era | Era that began about 66 million years ago, known as the “Age of Mammals” |
Extinction Rate | The rate at which species die off |
Mass Extinction | Occurs when a large proportion of the Earth’s species go extinct in a relatively short period of time |
Mesosauras | An example of a species that helped support the continental drift hypothesis |
Mesozoic Era | Era that began 245 million years ago, known as the age of the dinosaurs |
Paleozoic Era | Era that began about 544 million years ago and lasted for almost 300 million years |
Period | A subdivision of the eras in geologic time |