Introduction Discovery Timescale Terrane "I.D." & Activity Case Study: Wrangellia Geologic TImescale Glossary List References

Wegener is credited with the theory of continental drift (1912) from which the discipline of plate tectonics grows. Trained as an astronomer, he was also an explorer of Greenland and the Arctic, and had an interest in meteorology.

The sinking of the ocean crust edge as a result of convergence with lesser density. This process often causes earthquakes and can result in chains of volcanoes.

A process of spreading and thinning of the crustal plate. This forms a depression in the crust and often results in the separation of the crust into two or more smaller plates.

The geological term for mountain building, and it is usually associated with a specific historic event such as the Antler orogeny, or the Taconian orogeny.

Marine microfossils dating back to the Permian period (250 - 290 million years ago). They are used as index fossils during biostratigraphic dating of rocks.

Cratons are parts of the Earth's continents which have remained relatively stable and earthquake-free for long periods of time. They are usually thought of as the continental shield and the surrounding platform.

A theory presented by German scientist, Alfred Wegener in 1912. Using corresponding floral and faunal fossils, corresponding shapes of the east continental shelf of South America and the west continental shelf of Africa, and distinct geological features that crossed continental boundaries, Wegener proposed the continents had once been assembled in [..]

Conodonts are a group of extinct microscopic marine, worm-like animals that lived from 570 to 200 mya. Their fossil remains are used to date rocks.

A dating technique which uses index fossils to correlate the ages of rocks in different locations.