Cryptodomes are formed when viscous lava forces its way up and causes a bulge. The 1980 eruption of Mount St. Helens was an example. Lava was under great pressure and forced a bulge in the mountain, which was unstable and slid down the north side.
Volcanic cones (cinder cones)
Main articles: volcanic cone and Cinder cone
Volcanic cones or cinder cones result from eruptions of mostly small pieces of scoria and pyroclastics (both resemble cinders, hence the name of this volcano type) that build up around the vent. These can be relatively short-lived eruptions that produce a cone-shaped hill perhaps 30 to 400 meters high. Most cinder cones erupt only once. Cinder cones may form as flank vents on larger volcanoes, or occur on their own. Parícutin in Mexico and Sunset Crater in Arizona are examples of cinder cones. In New Mexico, Caja del Rio is a volcanic field of over 60 cinder cones.
Based on satellite images it was suggested that cinder cones might occur on other terrestrial bodies in the Solar system too; on the surface of Mars and Moon.
Stratovolcanoes (composite volcanoes)
Cross-section through a stratovolcano (vertical scale is exaggerated):
1. Large magma chamber
3. Conduit (pipe)
7. Layers of ash emitted by the volcano
8. Flank 9. Layers of lava emitted by the volcano
11. Parasitic cone
12. Lava flow
15. Ash cloud
Main article: Stratovolcano
Stratovolcanoes or composite volcanoes are tall conical mountains composed of lava flows and other ejecta in alternate layers, the