Term
|
Definition
| The method of measuring the age of an event or object in years. The actual age for a rock or mineral. |
|
|
Term
|
Definition
| The first geological period of the Paleozoic Era. Prior to this time, life forms were small and simple. After this time organisms became more common and complex. |
|
|
Term
|
Definition
| Era that began about 66 million years ago, known as the “Age of Mammals” |
|
|
Term
|
Definition
| A weathering process whereby rocks and minerals are broken down and transformed into new chemical combinations through chemical reactions. |
|
|
Term
|
Definition
| Theory that states that the gradual shifting of Earth’s plates causes continents to change their global positions over time |
|
|
Term
|
Definition
| The boundary formed by the collision of two lithospheric plates. |
|
|
Term
|
Definition
| The boundary between two tectonic plates that are moving away from each other. |
|
|
Term
|
Definition
| The largest division of geologic time. Earth’s 4.6 billion year history is divided into four eons. |
|
|
Term
|
Definition
| A subdivision of periods in geologic time |
|
|
Term
|
Definition
| A unit of geologic time that includes two or more periods. |
|
|
Term
|
Definition
| The standard method used to divide the Earth’s long natural history into manageable parts |
|
|
Term
|
Definition
| The process of the Earth changing over time |
|
|
Term
|
Definition
| The time needed for half of a sample of radioactive substance to undergo radioactive decay. |
|
|
Term
|
Definition
| Cylindrical samples of ice removed from ice sheets and glaciers. They are taken from regions that stay frozen year round and they contain detailed information about the history of the Earth. |
|
|
Term
|
Definition
| The forcing of molten rock into earlier rock layer formations. |
|
|
Term
|
Definition
| States that the oldest rocks lie on the bottom and the youngest rocks are on top of any undisturbed sequence of sedimentary rocks |
|
|
Term
|
Definition
| The erosion or breakdown of rock into smaller fragments by natural physical agents with no chemicals involved |
|
|
Term
|
Definition
| Era that began 245 million years ago, known as the age of the dinosaurs |
|
|
Term
|
Definition
| Era that began about 544 million years ago and lasted for almost 300 million years |
|
|
Term
|
Definition
| A subdivision of the eras in geologic time |
|
|
Term
|
Definition
| The theory that explains how large pieces of the Earth’s outermost layer called tectonic plates move and change shape. |
|
|
Term
|
Definition
| The process by which the age of a rock is determined by measuring the amount of radioactive isotopes present in the rock or rock sample |
|
|
Term
|
Definition
| The process in which a radioactive isotope tends to break down into a stable isotope of the same element or another element. |
|
|
Term
|
Definition
| Uses information about rock layers and the fossil record to determine the age relationships between rocks |
|
|
Term
|
Definition
| A fossilized mark that is formed in soft sediment by the movement or actions of an animal. |
|
|
Term
|
Definition
| The boundary formed by the tectonic plates sliding horizontally past each other |
|
|
Term
|
Definition
|
|
