Lithosphere and Hydrosphere Lithosphere The hard rock portion of the earth Geomorphology the study of the shape of the earth s surface Geomorphology is about how things get picked up move and get dropped off Time Geologic time o Earth was formed 4 7 billion years ago Earth s history is divided into periods from present going backward o Quaternary 0 2 Ma o Tertiary 2 66 Ma o Cretaceous 66 144 Ma o Jurassic 144 206 Ma or million years b p before present Quaternary Period o Epochs Holocene 0 10 000 years ago Pleistocene 10 000 years 2 Ma Earth s Structure What happens deep in the earth has a baring on what happens in the surface From center of the earth out The crust plates o Core relatively small and solid o Mantle large area surrounding the core Most of the earth is comprised of the mantle It is molten material melted rock Extremely high temperature and pressure o Asthenosphere boundary between the molten mantle and the solid material at the crust 70km 250 km o Crust the outermost layer Only up to 70 km deep Varies considerably Varies with regard to its age This happens because the crust is moving in plate tectonics o Series of plates on top of the molten mantle o There are currents active within the mantle that push the plates across the mantle which leads to the rock cycle o Subduction zones boundaries in which plates collide and one goes under the other o If you change the weight of the crust it can sink o Isostacy equilibrium between the weight of the crust and fluid underneath it o Isostatic rebound if you change the weight it will rebound So you take weight off it will raise This happens relatively slowly There are still places today that are in the rebound stage from the last ice age 18 20 000 years ago So we still see places on Earth that are increasing in elevation o Glaciation a net transfer of water from the ocean to the land This shift changed the distribution of weight on the crust Earth Materials Minerals a particular chemical combination that has a hardness density and crystal structure of its own Rocks made up of minerals Three types of rocks o Sedimentary Sediment is move across landscape and deposited someplace then it is compressed Limestone o Igneous formed by the cooling of molten material Magma v lava magma is lava that is still beneath the earth Intrusive v Extrusive material Intrusive from the mantle into the crust Formed by magma Extrusive formed from magma that has been expelled onto earth in the form of lava Basalt almost all of the sea floors are made up of Pumice extrusive igneous rock that is the result of basalt very fast cooling o Metamorphic igneous or sedimentary rock that has been exposed to great heat and pressure and changes chemical composition Granite gneiss Limestone marble Shale slate Igneous Features Pluton a very general term used for any igneous feature An intrusive igneous rock formation Batholith very large pluton Form core of many mountain ranges Greater than 100 km2 surface area Sill parallel to the strata igneous equivalent to the frosting in between layers of a cake Dyke crosses perpendicular to strata opposite of sill Laccolith lens shaped pluton MAKE SURE YOU READ ABOUT PLATE TECTONICS IN TEXT Plate Tectonics BOOK Subduction zones very geologically active places Earthquakes and volcanoes are extremely present in this location Almost all of the earthquakes and volcanoes in the pacific are located at the edge of plate boundaries Most spreading centers are under water but there are a couple of places that you can see spreading For example in Iceland the North American and European crusts are moving away from each other Processes about building the earth up and tearing the earth down Two processes of raising up the earth o Volcanoes transfer materials from the center of the earth up to the top o Diostrophism FOLDING AND FAULTING IN TEXT Volcano Forms at the end of a central vent or pipe that rises through the asthenosphere through the curst into a volcanic mountain o Lava o Gases o Pyroclastics some sort of rock that has been broken down and is solid Types of volcanic features o Cindercone a small cone shaped hill formed by the cinders that accumulate from moderately explosive eruptions o Caldera Large basin shape volcano ex Crater lake Types of volcanic activity dependent on material and viscosity o Effusive eruption Relatively gentle and produce large amounts of lava Often on the seafloor Lava tends to be low viscosity so it flows smoothly and quickly Forms shield volcanoes Shield Volcanoes Dome like Magma is low viscosity Lots in Hawaii o Explosive eruption Massive destructive eruption Typically occur inland of subduction zones Magma produces is much more viscous so it moves slowly Because of the differences associated with its chemical composition it can close up the vents of the pipe This causes the gas escaping from the magma to build up pressure and cause the volcano to erupt Ex mt St Helens Less lava but more pyroclastics and dust Composite volcano Also called strata volcanoes o A a lava Jagged lava flow o Pahoehoe lava flow very smooth lava flow Weathering The process by which the earth s surface or subsurface is either dissolved or disintegrated Mechanical Physical Weathering disintegration Dominant in conditions where it is dry and cool o No chemical alteration that occurs o When material is being disintegrated which means it is broken into pieces o Ex hitting glass with a hammer o Increases surface area of the material o Types of Mechanical weathering Frost Action Has to do with the expansion of water when it freezes Water expands its volume by about 9 when it freezes because molecules have to be in a certain configuration Ex when water gets into cracks freezes expands and enlarges the crack Crystallization important in arid areas Doesn t need to be cold Breaks the rock into pieces Hydration occurs when water is absorbed by the rock Some materials can absorb water which would cause them to swell Chemical Weathering dissolution material is actually dissolved Involves a change in the chemical structure of the rock Dominant in warm wet climates Due to chemical reactions between air water and the minerals in a rock o Hydrolysis the cutting of chemical bonds by water This breaks down certain types of minerals silicate minerals feldspar in the rock and causing it to dissolve o Oxidation combination of minerals with oxygen to form oxide Fe O2 Fe2O3 o Carbonation Mineral is dissolved into solution H2O CO2 H2CO3 Know the