Question | Answer |
lithosphere | layer of earth made up of crust and the rigid part of the upper mantle |
asthenosphere | layer in earth’s upper mantle that is soft because it is close to melting |
tectonic plate | one of large moving pieces of Earth’s lithosphere (oceanic/continental) |
continental drift | hypothesis that Earth’s continents move on Earth’s surface |
Pangaea | hypothetical super continent that included all the land masses of Earth, broke apart 200 million years ago |
theory of plate tectonic | theory stating that Earth’s lithosphere is broken into huge plates that move and change in size over time. |
rift valley | deep valley formed as tectonic plates move apart, such as along a mid- ocean ridge |
magnetic reversal | switch in the direction of the Earth’s magnetic field so that magnetic north and south switch |
hot spot | area where a column of hot material rises from deep within the mantle and heats the lithosphere, causing volcanic activity |
subduction | when oceanic plate sinks under another plate in Earth’s mantle |
fossil | an object that is a trace or remains of living things from the past. |
original remains | Fossils that are the actual bodies or body parts of an organism (ex. Bones) |
ice core | a sample of earth that is taken in a tube and shows the layers that have built up over thousands of years |
relative age (dating) | the age of an even or object in relation to other events or objects (younger or older) |
absolute age (dating) | the actual age in years of an object or event |
index fossil | Fossils of organisms that were common, lived in many areas, and existed only during a certain time span |
half-life | the length of time it takes for half of the atoms of a radioactive element to change to another form |
uniformitarianism | the theory that Earth is an always-changing place and that the same forces of change from the past are at work today. |
Geological Time Scale | the scale that divides Earth’s history into intervals that are defined by major events or changes on Earth |