Quick review for G107 Physical Geography Part III

1. Quick review for G107 Physical Geography Part III Draft Part III Draft by Isiorho. June 4, 2001

2. Soil • ‘And the Lord God formed man (woman) of dust (soil) from the ground..and out of the ground the Lord God formed every beast..bird’ • Soil: definitions… depends on the field • Soil is the upper layer(s) of the earth in which fine rock particles and organic material provide the basis for plant life (inorganic + organic + living things) Draft by Isiorho. June 4, 2001

3. Why different Soils • Five major environmental factors in soil formation • S = f(CROP)T • S = soil • F = function • C = climate • R = relief (topography) • O = organism (plants & animals) • P = parent materials Draft by Isiorho. June 4, 2001

4. Soil profile • Layers/colors in soil = soil profile • Pedon = 3-D representation of soil Draft by Isiorho. June 4, 2001

5. Soil Horizons • Soil Profile • Divided into three zones or horizons • O- accumulation of decaying matter (included in A horizon) • A- zone of Eluviations • B- zone of Illuviation • C- transition zone between solum or true soil and parent material • Solum or true soil is made up of A & B horizons Draft by Isiorho. June 4, 2001

6. Soil Properties • Color – black, gray, brown, yellow, blue, green, red, white • Black indicates the presence of organic (humic) matter i.e. fertile soil • Red indicates the presence of iron compounds • Texture • Size of individual grains: • gravel, sand, silt and clay • (gravel is not considered here) • loamy soil, silty clay, clayey sand Draft by Isiorho. June 4, 2001

7. Soil Properties • Structure • Crumpy, granular, • blocky, columnar, • prismatic, and platy Draft by Isiorho. June 4, 2001

8. Soil Properties • Chemistry • pH, Base ions (base cations) • Ca, Mg, K, Na- • clay minerals- illite, kaolinite, montmorillonite Draft by Isiorho. June 4, 2001

9. Pedogenic Regimes • Laterization (ferralitization) • Podzolization • Gleization • Calcification • Salinization Draft by Isiorho. June 4, 2001

10. Soil Classification • Soil Orders • Oxisols – heavy leaching… equatorial/tropics • Ultosols- clay accumulation… equatorial/tropics • Vertisols.. Tropics/subtropics • Alfisols.. Accumulation of clay… subhumids • Spodosols- cold moist climates • Mollisols- subhumid- semiarid..chernozem..prairie • Aridisols- dry climates • Histosols- large accumulation of organic… bog soil • Entisols- lack soil horizon • Inceptisols- some weakly developed soil horizon Draft by Isiorho. June 4, 2001

11. The Earth • Divided into three major layers • Crust- continental crust (Sial)(lighter than oceanic crust) and Oceanic (Sima) crust with • Crust plus upper mantle = lithosphere • Boundary between crust and mantle = Mohorovicic Discontinuity (MOHO) • Mantle • Lower (plastic) part of upper mantle = Asthenosphere • Core Draft by Isiorho. June 4, 2001

12. Plate Tectonic • Lithosphere = crust and upper mantle • Asthenosphere = the semi-liquid part of upper mantle • Lithosphere broken into large pieces called PLATES • Three types of plate boundaries • Divergent • Convergent • Transform Draft by Isiorho. June 4, 2001

13. Composition of the Crust • Eight elements (oxygen (47%), silicon (28%) aluminum, iron, calcium, sodium, potassium and magnesium) form the bulk of the minerals in the crust. • There are over 3000 known minerals • A mineral is a natural occurring substance that is inorganic, has definite chemical composition, and is crystalline Draft by Isiorho. June 4, 2001

14. Group of Minerals • Silicate- most important group- examples • Quartz, feldspar (orthoclase, plagioclase), Mica (Biotite & Muscovite), amphibole, pyroxene, olivine • Carbonate- calcite • Sulfides- galena & pyrite • Sulfates- gypsum • Oxides- hematite • Phosphate- apatite • Halides- halite • Natives- sulfur, copper, silver, gold Draft by Isiorho. June 4, 2001

15. Mineral Physical characteristic • Color • Streak • Luster • Hardness • Crystalline form • Fracture • Cleavage • Others- striations, smell, odor etc. Draft by Isiorho. June 4, 2001

16. Rocks • Rocks are aggregation of minerals, usually made of two or more minerals. • Three Rock Groups • Igneous • Metamorphic • Sedimentary Draft by Isiorho. June 4, 2001

17. Igneous Rocks • Igneous rocks are rocks that form from molten material = magma • The molten rock is magma when it is still within the earth and Lava when it exposed on the earth’s surface • Intrusive and extrusive • Can tell them apart using Texture (Phaneritic (visible with naked eye) and Aphanitic) Draft by Isiorho. June 4, 2001

18. Igneous Rocks Contd. • Examples of Intrusive igneous rocks • Granite, Diorite, Gabbro, Pegmatite • Examples of Extrusive Igneous Rocks • Rhyolite, Andesite, Basalt, Obsidian, Pumice Scoria Draft by Isiorho. June 4, 2001

19. Plutonic Rocks • Intrusive igneous rocks classified based on size, depth of formation and relationship to surrounding rocks Draft by Isiorho. June 4, 2001

20. Metamorphic Rocks • These are rocks that form as a result of alteration of existing rock due to high temperature and or pressure • Two types of Metamorphic Rocks • Non foliated and Foliated • Nonfoliated metamorphic rocks include quartzite, marble, anthracite coal • Foliation is the alignment of minerals • Examples of foliated met. Rocks- slate, schist, phyllite, gneiss Draft by Isiorho. June 4, 2001

21. Sedimentary Rocks • Produced from broken pieces of rocks or precipitates or • Lithification id the process whereby individual sediments are turned into solid rocks • Types of sedimentary rocks- clastic (detrital) & biochemical • Examples of sedimentary rocks- sandstone, conglomerate, breccia, siltstone, mudstone, shale, limestone, rock salt, bituminous coal Draft by Isiorho. June 4, 2001

22. Weathering and Mass Wasting • Weathering is the breakdown of rock or chemical decomposition of rock, thus two types of weathering: Physical (Mechanical) and Chemical • Physical • Chemical Draft by Isiorho. June 4, 2001

23. Physical weathering • Frost action • Salt action • Unloading • Plants • Animals • Heating & Cooling cycles (thermal) Draft by Isiorho. June 4, 2001

24. Chemical weathering • Other than the rock itself, water is the most important substance needed for chemical weathering • Hydration • Hydrolysis • carbonic • Solution Draft by Isiorho. June 4, 2001

25. Mass Wasting • The downward movement of earth material under the influence of gravity • Classified based on material type, velocity, water content • Types of Mass Wasting • Fall… • Flow……just like a river • Slump…this is what kids do in the park …remaining intact as shown in the diagram • Slide…rolling (turn over) … • Creep- this occurs imperceptibly Draft by Isiorho. June 4, 2001

26. Expanded Key Words & Phrases • Soil horizons, base cations, leaching, eluviations, Illuviation, soil colors and their meaning, pedogenic regimes or soil forming processes, minerals, rocks, plate boundaries, chemical weathering, mechanical weathering, karst terrain, plate tectonic, lithosphere, Sial (Continental crust) & Sima (Oceanic crust) with Sial being denser than sima, asthenosphere, Mohorovicic Dicontinuity (MOHO) the boundary between crust and mantle, Weathering (Physical (mechanical) & Chemical), climates favorable to physical weathering and chemical weathering, mass wasting…types and being able to identify them given drawing Draft by Isiorho. June 4, 2001