- Describe the physical structure of the Earth
- Apply an analogy to the age of the Earth and major events in the development of the biosphere
- Discuss the mechanism that drives plate tectonics
- Review the rock cycle in terms of the processes that form the three major rock types
- 8.1: Volcanoes
- Volcanism is directly related to the theory of plate tectonics. Volcanoes are found only at particular types of plate boundaries and rarely in the middle of ocean plates. In the following discussion we will summarize the three circumstances which explain the formation of nearly every volcano on earth. First, though, let’s go over the two types of volcanoes.
- 8.2: Volcanic Hazards
- As volcanoes modify the surface of the earth, they also enrich it, drawing people to live in volcanically active areas in order to cultivate the soil. The ash from volcanic eruptions provides vital nutrients to enrich and renew the soil, and soil formed from decomposed basalt (volcanic rock) is very fertile.
- 8.3: Orogenesis, Faults and Earthquakes
- Orogenesis is the term used for mountain building and is often the byproduct of a continent-ocean subduction zone, where a volcanic belt is formed. Orogenesis can also occur when continental plates collide with other continental plates (such as the Himalayas), or when ocean plates collide with ocean plates, forming island arc volcanoes. However, not all mountain belts are the result of active plate collisions.
Thumbnail: 10-meter (33 ft) high fountain of pāhoehoe lava, Hawaii, United States. Image used with permission (Public domain; Mbz1).