2 17 Geoscience Notes PP1 rock changes from solid to liquid form face diagram shows us what pressure and temp causes rock to change from solid to liquid Geotherm shows temp and pressure change in the crust 2 way to produce melt releasing pressure adding water Volcano Terms magma molten or partially molten rock from igneous rock form usually consists of silicate liq uid although carbonate and sulfide melts occur as well lava magma poured onto earths surface viscosity is a measure of resistance of a fluid to deform under shear stress it is commonly per ceived as Thickness or resistance to flow has something to do w mineralogy most minerals and rocks are made out of silicates creates tetrahedral easy to connect in high energy they don t connect easily when energy is lost more bonding occurs types of volcanoes shield volcano composite cone steeper slope often exists along ring of fire mount St Helen eruption takes 1 5 mins to go ten miles 1 3 of mountain lost process earthquakes and puffs of steam indicate magma is rising bulge develops erup tion causes second block to break free exposing more magma and initiating eruption column earthquake shakes mountain dislodging bugle which slides down mountain decreased pressure on magma initiates lateral blast cinder cone steepest slope biggest deepest craters basaltic flow very fluid like and can travel a great distance forming a thin sheet andesitic flow is too vicious to travel far and tends to break up as it flows rhyolitic spire in some cases rhyoltic lava is too vicious to flow at all and rises out of the vent as a columnar plug rhyolitic dome rhyolitic lava is so viscous that it piles u p at a vent as a dome volcanic dome steep sided mound built by magma PP2 little prince quote if they are well cleaned out volcanoes burn slow and steadily cant go down mantle b c before explosion it is a solid rock exsolution surface when magma isnt strong enough to keep gas bubbles in place we get an eruption gas moves out at really quick scale 2 19 gas accelerates quickly and takes things with it into atmosphere where pressure 0 a lot of material comes back down and moves along surface some material goes into a different sphere with a diff pressure which allows it to stay in atmos phere and move further around world base surge ash cloud that builds when trust material comes really fast to surface and moves different material around when material comes back down it produces high energy base surge accounts for majority of damage not initial explosion itself goes up to 300m s if you add rain or water or other material it is worse and produces lahar hot and cold mixture of water and rock fragments flowing down the slopes of a volcano and or river valley biggest problem most destructive part is the fast moving lahars can be so fast it literally freezes people in place covered in rock ash Pompeii lake natural disasters relate to e o after specific explosion everyone is found dead what happened is that lake by volcano is den sity stratified lake and highest density is on top was sitting on top of crater CO2 was seeping into lake but it got trapped under top layer at a certain point pressure becomes too big and lower density material suddenly goes into area CO2 killed everyone solution create fountains with straw to bottom which allows CO2 to constantly come out put signs and CO2 detectors around lake too bad barely anyone can read 2 26 changes and differences among volcanoes might come from difference in materials shield volcanoes A a lava gentle slope blocky lava hoy hoy lava ropey rock that we passed around that looked like intertwining rope layers of lava innermost liquid lava then plastic crust then brittle crust center and point of energy stays hot and hot material wants to move forward and hot material starts to pour out graph with shear stress vs viscosity shows that we need much more force to produce A a lava also viscosity is dependent upon temperatures people can actually escape volcanoes in hawaii much easier gas behavior is big part of ocean life bubbles give our sulfur sea floor moving volcano slowly moves into water and as the volcano get colder and colder in starts to sink more and more into the ocean floor hawaii is associated with long chain of underground volcanos we can use radioactive decay to date volcano oldest volcano is furthest on the chain youngest is still above ground and active 3 10 Atmosphere Aristotle founder of the science of exploring and thinking about the climate combined all materials into four components fire air water earth now we use energy gas liquid solid Aristotle s division of four groups was a good start to explaining the earth composite of atmosphere is actually predominately nitrogen then oxygen a little Co2 and Argon them in our atmosphere theory is that we used to have a lot more gases but gravity wasn t strong enough to keep without our atmosphere we wouldn t have water or be able to burn things atmosphere is more important than we think of it being Human Influence on Atmosphere amount of CO2 in atmosphere is increasing this makes us question are humans responsible for the increase or is it a natural occur rence life strongly influences the composite of the atmosphere years ago earth developed plants which provide oxygen into the atmosphere life takes up certain components and releases other ones results in change of atmosphere composition of atmosphere is different in different areas air in the forest is easier to breath and has more oxygen than city one main thing that influences the atmosphere is water and evaporation red sunsets rises are red b c of Aerosols Aerosols only red light is able to pass through aerosols so when it is clear and when the sun hits them right the sky appears red in dust dry air aerosols are more visible sunsets aren t as great when its foggy out Ozone O3 if you look at planets closer to sun like Mercury almost everything is burnt we don t burn up because we have the protective layer of ozone around our earth oxygen ultraviolet atomic oxygen atomic oxygen oxygen molecule ozone our ozone cycle is constantly recycling so we have a constant level of ozone we need other elements can have an effect on ozone such as CO2 a couple of years ago we had an issue with an excess amount of chlorine which caused a depletion of ozone to increase this caused an ozone hole we now need stronger sunscreen b c ozone layer is weaker which causes intensity of sun global community has decided something