STUDENT SOIL PRESENTATIONS

Transcription

1 STUDENT SOIL PRESENTATIONS

2 Soil Order (and informal name) Student Name(s) Alfisol = deciduous forest soil Andisol = formed on volcanic ash Aridisol = desert soil Entisol = alluvium soil Gelisol = tundra soil Histosol = organic soil Inceptisol = young soils Mollisol = prairie soils Oxisols = tropical soil/laterite Spodosol = coniferous forest soil Ultisol = sub-tropical Vertisol = swelling soil

3 Soil Presentations During Lab on April 7, you will give an oral presentation about one of the 12 soil orders (categories). Presentation must be 3-5 minutes in length with several minutes for questions. The time limit will be enforced strictly. For the presentations with two students, each student should give ~half of the presentation. All presentations of soil orders must include the following: a) Soil Order Characteristics - including presence and development of soil horizons, soil fertility, any other significant soil properties, and any characteristic age, vegetation and soil minerals, if applicable. b) Environment of Formation - features of climate, bedrock composition and topography, if applicable. c) Distribution in USA and World - Locations in USA and world where soil order occurs and why it occurs there.

4 Soil Presentations Grading 25 pts. for Content (based on accuracy and coverage): 9 pts. for Soil order characteristics 9 pts. for Environment of Formation 7 pts. for Distribution in USA and World 5 pts. for Style (use of effective opening and closing statements, organization, delivery) Total = 30 pts Up to 5 Extra Credit points may be given based on creativity, handouts, visual aids, or other special features of the presentation.

5 Soil Presentations You must also turn in a typed outline of your presentation before you give your presentation. The outline should include all of the key information in your oral presentation, and it should be in a similar sequence as your oral presentation. Make sure to give an effective presentation, which includes a good opening and closing as well as good organization. You should practice your presentation to ensure that you are within the time guidelines and that you deliver it effectively. Prof. Altaner will attend the presentations.

6 Soil Presentations If you want to give a Powerpoint slide presentation, then you must send your Powerpoint file to Mike by 5 pm on Monday, April 6 so that he can load these files onto his laptop computer, which will be used for all Powerpoint presentations. Give your Powerpoint file a descriptive name that includes your soil order and your last name, e.g., Histosol_Altaner. If you would like black and white copies for handouts of your PowerPoint presentation, put the originals in Mike s mailbox in 144 CAB (or give them to Mike in person) by Noon on Monday, April 6. He'll have the copies ready for your presentation in Lab.

7 Geol 333 Lab 9 Carbonate Sedimentary Rocks in Hand Sample and Thin Section

8 Sedimentary Rock Classification and Textures Clastic - transport, deposit, and lithify sediment Chemical - chemical precipitation, dissolved ions combine to form minerals; crystalline texture (interlocking, ~igneous) Organic (biochemical) - accumulation of plant or animal remains, e.g., CaCO 3 shells; Fossiliferous limestone has bioclastic texture - CaCO 3 shells with pores filled with spar (calcite cement) or micrite (finegrained CaCO 3 mud); chemical + organic sedimentary rocks are classified by composition (~single mineral) Due to abundance and geologic significance, Lab emphasizes Carbonate sedimentary rocks (limestone and dolostone) with chemical and organic origins.

9 Carbonate Rock - Nature + Origin Limestone = ~CaCO 3 (calcite, sometimes aragonite); forms in ~shallow, warm ocean water far from clastic sediment sources Dolostone = ~ CaMg(CO 3 ) 2 (dolomite); forms during burial by alteration of preexisting limestone by Mg-rich water Limestone and Dolostone usually consist of: Allochems = sand-sized or coarser carbonate grains (framework grains in sandstone), includes CaCO 3 shells and oolites, ~1-2 mm spherical grains of inorganically precipitated, concentric layers of CaCO 3, often with quartz grain in middle, precipitation nucleus Micrite = fine-grained carbonate mud (matrix in sandstone) Spar = crystalline carbonate cement (cement in sandstone)

10 Carbonate Rock Classification (Fig. 1.3) Biomicrite/Biosparite = abundant CaCO 3 shells with micrite or spar; won t emphasize fossil shell identification (Coquina = porous and poorly cemented limestone, ~all CaCO 3 shells) Oomicrite/Oosparite = abundant oolites with micrite or spar Micrite = ~entirely CaCO 3 mud (chalk = soft and poorly cemented limestone, tiny shells of marine plankton) Crystalline Limestone or Crystalline Dolostone = interlocking crystals of calcite or dolomite; hard to distinguish dolomite from calcite in thin section, unless stained. Use acid reaction to distinguish dolomite from calcite in hand sample.

11 Geologically Important Fossils (Fig. 8.1)

12 Carbonate Rocks in Thin Section PPL Calcite - high relief and high birefringence, 60/120 cleavage; crystalline texture and spar cement texture (p in MacKenzie & Adams, 1994) PPL XPL

13 Carbonate Rocks in Thin Section Micrite (p. 137 in M & A) PPL

14 Carbonate Rocks in Thin Section PPL CaCO3 Shells (Bioclasts) (p. 133 in M & A) Rock Names? PPL

15 Carbonate Rocks in Thin Section PPL Oolites (p. 131 in M & A) Rock Names? PPL

16 Carbonate Rocks in Thin Section All are PPL Dolomitic Limestone (upper photos) Crystalline Dolomite (lower photo) (p. 139 in M & A)

17 Depositional Environment Limestone (and Dolostone) shallow, warm seawater; Broken fossils, spar cement and oolites indicate active water, e.g., shallow water with waves Unbroken large fossils and micrite indicate quiet water, e.g., lagoon or deep water

18 Other Chemical and Organic Sedimentary Rocks Chert = fine-grained quartz, forms by recrystallization of siliceous fossil skeletons + inorganically precipitated silica Rock Salt and Rock Gypsum = (evaporites) form by precipitation of halite or gypsum from evaporating seawater Banded Iron Formation = alternating layers of Fe-oxides and chert Peat = partly decomposed plants, converts to coal during burial Lignite, Bituminous, Anthracite = grades (rank) of coal, colors range from brown to dull black to shiny black