volcanology Flashcards
what is volcanology
process by which solids, liquids and gaseous materials are forced into the earths crust or ejected onto the surface
what is magma
molten rock below the earths surface
what is lava
molten rock that has reached the earths surface
igneous rock?
extrusive and intrusive materials cooled from magma
compare basaltic to andesitic lava
- Basaltic Lava hotter at about 1200 degrees, not as thick and flows fast low silica content found at constructive margins takes long to solidify less viscous - Andesitic Lava cooler at about 800 degrees, thicker and flows slower high silica content found at destructive margins solidifies quickly viscous
pyroclastic material
material ejected by a volcano in a fragmented form
list 6 different types of volcanoes and explain each
Fissure - 2 plates move apart forming a slit like opening, and basaltic lava flows over a long distance down a gentle slope
Shield - central vent, gentle sloping sides built up by numerous basaltic flows
dome - acid lava quickly solidifies forming a steep slope
cinder cones - slightly concave, built up of layers of fine ash and cinders
composite cones - cone shaped, formed by alternating ash and lava eruptions forming layers
calderas - built up of gases, explosion clears the summit of the volcano forming large crater like shape
hydromagmatic?
any eruptive process in which magma and lava interact with external water
Sill?
horizontal sheet intrusion along bedding plane with vertical cooling cracks, cools rapidly on outside on contact with surrounding rocks
dyke
vertical sheet intrusion with horizontal cooling cracks, cooling rapidly on contacts with surrounding rocks
batholith
deep seated and surrounded by hot rock, magma cools slowly so that large crystals form and that there is a large metamorphic contact zone
