NATS 1570 Lecture 4: Lecture 4

• School: York University
• Department: Natural Science
• Course: NATS 1570
• Professor: Mary- Helen Armour

Document Summary

All volcanoes are the result of magma becoming liquid under the surface, rising and erupting as lava (often very forcefully) at the surface. The mechanism that produces the magma and the local geology where the magma exits the crust can produce a number of different structures. There are 3 main types of volcano. There are also other structures that result from large scale eruption of lava producing much larger feature, but no distinctive cone. All volcanoes have some basic features in common. Magma escapes through fissures and cracks in the crust. Usually creates circular conduits or pipes along which the magma flows. Lava erupts at the surface through a vent. Schematic figure of a stratavolcano illustrating some volcanic terms and rock names. Rock names are based on the weight per cent of silicon dioxide (sio2) in the rock. (courtesy of the cascade volcano observatory, united states geological survey) from.