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Lithosphere Notes Package Covers Lithosphere notes spanning March 1st, 3rd and 8th with the following topics: -The Rock Cycle >Physical/Chemical Weathering >Erosion >Karst and its Formation >Mass Wasting and itsControlling Factors and Classes (includ

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Sarah Finkelstein

Lithosphere (March 1 , 3 , 8 cover Lithosphere) Lithosphere: the solid earth. What processes occur on the ground? What shapes the Earth’s surface? Endogenic processes: processes occurring inside Earth having to do with several things such as geophysical movement of fluids, plate techtonics, formation of rocks, tectonic uplift (creates mountain ranges/sea floor spreading). These happen very slowly and are in traditional realm of geology. Exogenic processes : things happening above surface/outside innards of earth. >Geomorphology: process-based study of landforms (earth + shape). -constant supply of raw materials that’re then worked -dynamic equilibrium between uplift of tectonics and wearing down by weathering, mass wasting and erosion (rock moved with an agent: water/wind/ice move rock) The Rock Cycle -2 diff. types of plates make up lithosphere: oceanic crust (heavier) and terrestrial crust (hard brittle crust plate tectonics float atop molten, plastic asthenosphere). >when these come into contact, interesting stuff happens > plate tectonics: solid sea-floor gets subducted beneath land plates, then melts > weathering, mass-wasting and erosion wear down solid rock that’s uplifted by the rock cycle. No tectonic activity would mean earth would be totally flat plain, w/o that uplift. > molten rock underneath, brittle plates on top in asthenosphere Weathering -Higher, taller, more jagged ranges means newer mountains. Flatter, rounded and low ranges mean older mountains. Rockies = newer vs. Appalachians = older. -process wherein solid rock breaks down and forms smaller rocks, called regolith (weathered rock). -divide weathering into two forms, physical and chemical. These forms interact in nature and can be observed working simultaneously. Physical (mechanical) weathering: breakage, rocks disintegrate w/o chemical alteration >e.g. physical altering of rock; e.g. water freezes inside rock and breaks from inside (frost-action) Erosion -weathered rock is subject to erosion -refers to the transportation/removal of broken material by diff. forces; >Agents of Erosion: wind, water, ice -Bedrock w/weak areas due to gaps (JOINTS) where water can enter  breaks into regolith  vegetation promotes weathering by worming into gaps (Biosphere & lithosphere work together) 1).Frost action: role of joints; wedge-axn breakage e.g. Toronto road potholes by frost-axn 2). Salt-crystal growth: in arid climates, expansion/crystallization of solutes left Lithosphere (March 1 , 3 , 8 cover Lithosphere) behind by heightened evaporation promotes weathering. Salt-expansion grows chemically. 3). “Unloading”: release of weight and pressure on a rock surface. Rock surface has a lot of easily erodible material on top. Once all of it’s gone, rock below can ‘relax’ and spaces between the molecules of rock can expand, shedding rock in the process of ‘relaxing’/expanding. As expansion goes on, pushes off upper layers of rock in sheaths. Chemical weathering: interaxns ‘tween air and water chng. rock chemically. >e.g. water contains solutes that can be slightly acidic which can chng. rock chemically -Water = very potent agent of chemical weathering b/c it’s a solvent; propensity for acidic solutes. Water is very good at slowly forcing change. - Chemical weathering increases w/increased temp. + ppt. 1).Hydrolysis: chemical rxn w/water + carbonic acid e.g. Feldspar weathers  clay + sand. Water produces these new minerals from Feldspar; over time breaks down granite (which contains Feldspar). 1.5) Hydration: water molecules come into the crystal structure/lattice of minerals, changing the properties of the mineral so it can expand/be more susceptible to other types of weathering (physical) 2). Oxidation: rxn of metals with oxygen - e.g. free oxygen in air takes e s from elemental Fe in rocks & minerals;  iron oxide Iron oxide = softer thus more easily removed rust  enhances oth. forms of weathering (physical) 3).Carbonation/Dissolution: rxn with a weak acid; moisture in atmosphere w/carbon dioxide. Dissolution of calcium carbonate & removal in solution. e.g. Carbonation esp. good at removing carbonate-containing rock; Niagara Escarpment. > weak acid particularly good at dissolving rocks. Sedimentary rocks containing carbonate such as those making up Niagara Escarpment (made out of ‘dolomite’), and bedrock in Toronto. Sources of acid: rain water, humic acids (weak yet effective for carbonation) in soils (plant decomposition) >Importance of soils for weathering: soils right @ interface where weathering taking place in biosphere Spheroidal weathering: chemical rxn with water falling as ppt. creates smooth, rounded edges where water continuously falling over rocks (Niagara Escarpment) -Ppt. vs. Temp. graph: >wetter/hotter conditions = most chemical weathering. *physical can happen in warm/dry places b/c of salt-crystal expansion, otherwise, graph is a good representation of the general distribution of both types of weathering. >Dryer/cooler = more frost-axn = most physical weathering. Lithosphere (March 1 , 3 , 8 cover Lithosphere) Karst landscapes: explain caves, underground caverns etc. hollowed out by carbonic acid that comes with rainfall/water - Chemical weathering of surface and sub-surface limestone by carbonic acid *role of ground water -“Lost Rivers” – where streams create waterfalls un
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