Presentation on theme: " The sequence of events by which rocks are initially formed, altered, destroyed, and reformed as a result of magmatism, erosion, sedimentation, and metamorphism."— Presentation transcript:
The sequence of events by which rocks are initially formed, altered, destroyed, and reformed as a result of magmatism, erosion, sedimentation, and metamorphism.
Liquid rock underground is called magma! Liquid rock above ground is called Lava!
viscosity is "thickness" or "internal friction". Thus, water is "thin", having a lower viscosity, while Honey is "thick", having a higher viscosity. Put simply, the less viscous the fluid is, the greater its ease of movement (fluidity).
Kinds of Lava Pyroclastic,Superheated rock and ash that explodes from a volcano. This type of lava has many gas pockets and makes what we know as pumice, Pyroclastic Igneous rock. Example of Pyroclastic flow was from Mt. St. Helens http://www.youtube.com/watch?v=xP2dr eOI8gI http://www.youtube.com/watch?v=xP2dr eOI8gI
Aa- In Polynesian this means lava you cannot walk on in bare feet- its is sticky and moves rather slow. Instead of flowing like a river it tends to pile up at its flow front and this leads to an upper surface that is rougher than #1 grit sandpaper, an angular jagged lava spikes sticking up out of the surface.
Pahoehoe- In Polynesian this means lava you can walk on with bare feet. Pahoehoe forms the "rivers" or " streams " of flowing lava so often see in pictures of Hawaiian Volcanoes.
Pillow Lava Pillow lava is typically found erupting from underwater volcano vents. As soon as the lava contacts the water, it’s cooled down and forms a hardened shell. As more lava issues from the vent, the shell of lava cracks and more “pillows” come out of these crackswater
Felsic lava is high in silicates and is very viscous (thick )
Thinner and less viscous not as much silicate. Shield volcanoes are composed of mafic lava.
rarely do volcanologist get to watch the birth, growth, and death of a volcano. Paricutin provided such an opportunity. The eruption that created Paricutin began in 1943 and continued to 1952. Most of the explosive activity was during the first year of the eruption when the cone grew to 1,100 feet (336 m). The cone continued to grow for another 8 years but added only another 290 feet (88 m). Effusive activity began on the second day and continued to the end of the eruption. Lava flows covered about 10 square miles (25 square km) and had a volume of about 0.3 cubic miles (1.4 cubic km). The rate of eruption declined steadily until the last 6 months of the eruption when violent explosions were frequent and violent. No one was killed by lava or ash. However, three people were killed by lightning associated with the eruption.