D1-1
Internal and External Processes
Mt. Yasur, a volcano in Vanuatu, was formed by internal processes inside the Earth.
The Earth is a dynamic sphere that undergoes constant change. The landforms on the Earth’s surface are being constantly modified by two opposing processes:
- Internal Processes: Internal processes generally create elevated landforms such as mountains and volcanoes. Internal processes get their energy from the Earth’s interior. (Further information about the Earth’s internal processes can found in Unit B – Plate Tectonics, Unit E – Earthquakes, and Unit F – Volcanoes.)
- External Processes: External processes generally lower the elevation of the land surface. These processes break rock and soil apart and move this material to lower elevations.
What Do You Think?
K2, the second highest mountain in the world (8,611 m/28,251 ft), was formed as a result of tectonic plates colliding.
A Peak Experience
Mountains can form when tectonic plates collide with one another.
- Click here to view the Himalayas Mountain Range.
- What plates are colliding in order to produce the Himalayas? (Note: You may have to zoom out in your view in order to properly see the plate names.)
The Eurasian Plate and the Indian Plate are colliding to produce the Himalayas. - Which plate is being subducted (i.e. moving under another one) in order to form the Himalayas? What do you think? Explain your reasoning. The Indian Plate is being subducted under the Eurasian Plate. Since the Himalayas are located on the Eurasian Plate, this means that the Indian Plate must be sliding under the Eurasian Plate. If the Eurasian Plate had been the plate being subducted, then the Himalayas would have been located on the Indian Plate.
- Click on the name of each mountain range in the chart below, and then follow the process you used in questions 1 and 2 to complete the chart:
Mountain Range Which plates are involved in the collision? Which plate is being subducted? Andes South American Plate and Nazca Plate Nazca Plate Cascades North American Plate and Juan de Fuca Plate Juan de Fuca Plate Alps Eurasian Plate and African Plate African Plate