Chapters 4 7 03 08 2014 Ch 1 Intro to Geology Physical Geology o Materials composing earth o Processes that operate beneath and upon its surface Historical Geology o Origin of Earth and its development through time o Physical and biological occurrences o How the earth changes Catastrophism Earth was formed by major events Uniformitarianism Earth was formed slowly over many years The present is key to the past Theory by James Hutten Theory Is formed through rigor and testing It stands because it has not been disproven Spheres o Hydrosphere all of water on earth Ground water saline water surface water etc o Atmosphere The gaseous part of earth o Geosphere The composition of earth s interior What the inside of earth is made out of o Biosphere Anything living Nebular Theory Big bang collapsing starts materials turned Igneous Rocks rocks formed by the cooling of melting earth o Magma under surface cools slowly Creates coarse grain o Lava on top of surface cools quickly Creates fine grain rock into planets materials rock Metamorphic Rocks solid state changes to a preexisting rock due to increased pressure temp or differential stress o A new rock from a preexisting rock Sedimentary Rocks formed from sentiments that are moved then compacted into a rock Ch 2 Plate Tectonics Lithosphere crust and upper sold mantle Mantle Asthenosphere on top Outer core Inner core Plate Tectonics the explanation of how earth works Earth s outer shell is broken into rigid plates that move Plate motion defines three types of boundaries that change the face of the planet Divergent convergent transform Continental Drift Proposed by Alfred Wegener in 1915 States that a supercontinent called Pangaea once existed but has since broken apart Evidence Supporting Wegener s Theory o Jigsaw puzzle he noticed that the continents fit together o Fossils identical fossil organisms are found on continents now separated by vast oceans o Geologic Features he found vast mountain ranges that would have once been one mountain range o Ancient Climates Ancient climates fit together with the jigsaw theory o Glacial Evidence glacial evidence on different continents would have fit together at one time Also glacial striation Wegener s wrong hypotheses o Said the sun and moon were capable of moving the continents o Suggested the continents broke through the ocean crust Theory of Plate Tectonics Developed in 1960 by Harry Hess in his Essay on Geopoetry Lithosphere Earth s strong outer layer Oceanic Lithosphere plates more dense than continental plates Asthenosphere a hotter weaker region of the mantle under the lithosphere Know the plates Eurasian Australian Indian North American Pacific Cocos Nazca Caribbean South American African Eurasian Arabian What drives plate motion Convection differences in heat Hot things rise Slab Pull as part of a plate begins to sink it pulls the rest behind it Ridge Pull a gravity driven force that results from the elevated position of the ridge Divergent Plate Boundaries Constructive Mid Ocean Ridge Seafloor spreading Continental Rifting magma melts continental crust which weakens and stretches it Continued spreading creates a long narrow sea similar to the Red Sea Eventually an ocean is created between the to continents Mid Ocean Ridges o New crust is created as magma comes out between the two plates It cools and becomes new crust Newer rock is found close to the separation and older rock is found equally far away on both sides of the break Convergent Plate Boundaries Oceanic Continental destructive Margins when denser oceanic crust comes in contact with a less dense continental crust the more dense crust will subduct Oceanic Oceanic one plate will be denser and subduct Forms volcano s Continental continental two very buoyant continental crusts that wont subduct Instead the go up creating Mountains Transform Plate Boundaries Neither destructive nor constructive Creates fracture zones Hot Spots Abnormally hot regions that are not forming a plate boundary Often not found near a boundary As magma moves toward the surface a volcano is eventually formed As the crust above moves and the hot spot stays stationary a new volcano will be formed This will create a line of volcano s Paleomagnetism Basaltic Rocks magnetite iron rich mineral that is affected by Earth s magnetic field When it is still hot the minerals will align to the current magnetic field and stay that direction once it dries Sometimes Earth s magnetic field will reverse We can measure when this happens based on these magnetite rocks Apparent Polar Wander Initial different north poles over time Ch 3 Minerals Mineral Definition Generally inorganic o It can t have carbon hydrogen bonds C H o Minerals can have a biological origin Naturally Occurring o Ex Diamond v Cubic Zirconia Solid o Doesn t change shape o Ex Water is not a mineral but ice is Crystalline Structure o Atoms must have a fixed atomic structure that repeats itself o Ex Glass is not a mineral because the atoms don t align in space perfectly Definite chemical composition o We can write out the chemical formula of the mineral o Not a mineral if it doesn t satisfy these conditions Q Is it a mineral o Asphalt shingle on a roof NO chemical formula o Sugar crystals in a sugar cube NO organic o Ice making up a snowflake YES meets criteria o Salt on your food YES o Petroleum Oil NO liquid Mineral Formation Precipitation from an aqueous solution chemical sedimentary rock o Formed from evaporating water and elements Crystallization of molten rock igneous rock o Lava cools crystals cool that form minerals then eventually rocks Biomineralization biochemical sedimentary rock o Minerals formed from a biological source o Ex Some birds secrete minerals Solid state diffusion metamorphic rock o Rearrangement of atoms to form a new mineral Q Minerals are building blocks of rocks solid inorganic crystalline naturally occurring Q Minerals can be formed by aqueous precipitation crystallization from a melt or biomineralization Mineral Properties Properties are determined from chemical composition and crystal structure bonds Luster o Metallic or Nonmetallic Transmission of light o Transparent v Translucent v Opaque Color Streak Tenacity Crystal Shape or Habit o Cubes v Octahedra v Blades v etc o Is it bendable or will it break Hardness o Mohs scale Cleavage ability to break along planes o Can be very useful on some minerals o Some don t have cleavage planes Density and specific gravity Magnetism HCL dropper on