announcements Someone reminded me yesterday that we’re in the 6th week of classes already I need to give you another exam, so that we can drop one…so… WEDNESDAY MARCH 7 (so I can be sure it get it back before spring break). Review Monday 5th, 5 PM, here. Turn in your Pinatubo video worksheet please READ: chapter 3, p (don’t panic, lots of pictures)

Today/Friday (there is an outline on the website) What are the different materials that come out of a volcano? What are the compositions involved? What are different kinds of volcanoes? Where do they erupt? What makes a volcano erupt the way it does?

What are the different materials that come out of a volcano? Terms to memorize… Pyroclast: anything exploded out of the vent –ash (very small fragments) –lapilli (small rocks) and bombs (large rocks) –pumice and cinder –ash flow, also called pyroclastic flow –ash-flow tuff, also called pyroclastic-flow deposit

pumice fall ash-flow tuff cinder cone

What are the different materials that come out of a volcano? Terms to memorize… Lava: magma that is effused (that flows) out of the vent, no explosion –crystal size depends on cooling speed

lava flow a few thousand years a few thousand seconds

What are the different materials that come out of a volcano? Terms to memorize… Lahar: Indonesian word for volcanic mudflow: ash + water, + whatever else is around; needs a slope

Candi Morangan, Indonesia, where lahar met a Hindu temple in ~860 AD Mount St. Helens, 1980

What are the different materials that come out of a volcano? Gases –dominantly H 2 O and CO 2, plus CO, SO 2, H 2 S + HF

nice-looking lake, yes?

What are the compositions of volcanoes: what are magmas made of? More terms to memorize Basalt Andesite Dacite Rhyolite What do these words mean and what do they tell us about volcanoes?

What are the compositions of volcanoes: what are magmas made of? Basalt Andesite Dacite Rhyolite You need a note-taker, a leader, an assistant, and a time-keeper/reporter for this

Fruit salad 20% blueberries 20% strawberries 20% kiwis 20% bananas 20% apples

Basalt highest-temperature magma: all magma starts life as basalt high-temperature minerals are really easy to form, but hard to preserve if you take all the blueberries out of a fruit salad, what you have left over will have 0% blueberries and 25% strawberries, 25% kiwis, 25% bananas, and 25% apples

Andesite moderate-temperature magma moderate-temperature minerals form from the high-temperature ones as the magma cools take the blueberries and the strawberries out of the fruit salad, what you have now is 33% kiwis, 33% bananas, and 33% apples

Dacite cooler-yet-temperature magma cooler-temperature minerals form from the moderate-temperature ones as the magma cools take the blueberries and the strawberries and the kiwi slices out of the fruit salad, what you have now is rich in 50% bananas and 50% apples

Rhyolite: the 50% bananas and 50% apples left in the fruit salad you started with 20% of 5 different kinds of fruit coolest-temperature magma coolest-temperature minerals form from the cooler-temperature ones as the magma cools chains of silica