Rodrigo Rivera-Reyes GEOL 1104/1114 Updated October 2012 GEOL LAB Midterm 1 Study Guide 1. Scientific Method. O Observation.- Something is noticed and causes a question to be asked. H Hypothesis.- Proposed SOLUTION to the question. P Prediction.- What would occur if my hypothesis is correct. E Experiment.- Predictions are tested and data gathered. E Evaluate.- If hypothesis is correct-> look for another prediction and test it. If hypothesis not correct-> Modify and re-test it. *Theory= If all available testing support a hypothesis. *Law= Theory that continually passes all tests over long periods of time. Using an example: Observation.- Why won t my car start? Hypothesis.- Maybe because it is out of gas. Prediction.- If I am out of gas, my gas level indicator should be on Empty. then Experiment and finally Evaluate 2. Dynamic Ocean Floor. *Mid-ocean ridges.- Chain of submarine mountains. Associated with Divergence <- -> *Deep-ocean trench.- Long, narrow depression in the ocean floor. Convergence -> <- *Earthquakes.- distribution and depths *Paleomagnetism.- Ancient magnetism. It is used to determine the rate at which plates are forming and moving away from the ridge crest.
*Rates of Spreading.- Use ruler only based on the scale given (no calculation needed) *Distance over time.- Dist.(cm) / Time (yr) Instructions: Multiply km by 100,000 and divide by years. *Hotspots.- arises from a plume of molten material moving upward from the mantle and remains constant for millions of years. *Min/Max Velocity.- V= cm/yr Plate boundaries: Convergent.- -> <- Mountain formation in continental. Subduction in oceanic Divergent.- <- ->. Construction of oceanic lithosphere. Transform.- up and down. Q. Relationship between Igneous rocks and volcanism - Igneous rocks are formed through the cooling and solidification of magma or lava. 3. Minerals. *Luster.- Manner in which light reflects from a mineral surface. Types: Metallic, Non-Metallic most common. *Hardness.- Degree of resistance of given mineral to scratching. Use of the Mohs Scale F Fingernail= hardness of 2.5, P Penny= 3.5, I Iron Nail= 4.5 G Glass= 5.5 and S Streak plate= 6.5. *Hard minerals have a hardness of 5.5 or greater and scratch glass. *When scratching mineral against object. If it powders= Softer than object. If it scratches= harder than object. *Streak.- Color of mineral in powdered form (use the streak plate for results). *Cleavage and fracture.- Tendency of certain minerals to break in distinct planes. Cubic 3 Directional 2 Direc. 1 Direc. Halite-> Calcite-> Fieldspar-> Mica-> Remember Fracture: Break in random places instead of cleaving. Obsidian Quartz
*Color.- Just the color of the mineral. *Other properties: -Striation: parallel groves Minerals Classification Table Name Luster Hardness Streak Cleavage/ Fracture Color Picture Augite / Pyroxene n-m 5.5 - Good Black Green Biotite/Mica n-m 2.5 no streak 1 direction Black Calcite n-m 3 White Perfect C. White Fluorite n-m 4 no streak Perfect C. Green Galena m 2.5 gray/black Perfect Black
Name Luster Hardness Streak Cleavage/ Fracture Color Picture Garnet m 3.5 no streak uneven brown/ green Gympsum n-m <2.5 White Perfect White Halite n-m 2.5 White Perfect Cubic white clear pink lightblue Hematite m 6< Red/Brown None Black Magnetite m 5.5 black None Black Muscovite n-m 2.5 White Perfect C. White Gray Silver
Name Luster Hardness Streak Cleavage/ Fracture Color Picture Olivine n-m Glassy 6< White Good Yellow Green Orthoclase (Potassium Feldspar) n-m Glassy 6 White Perfect Pink Plagioclase n-m Glassy 6< White Good White Pyrite m 6< green/black Conchoida l Fracture Yellow Quartz n-m 6< White Conchoidal Fracture - Talc n-m Pearly <2.5 White Perfect C. White *n-m: Non-metallic *m: Metallic 4. Igneous Rocks. Color Index of Igneous Rocks: *Mafic.- rock with dark-colored minerals. = Magnesium + Iron Remember what MAFIC rocks are made off! Made with: Olivine Pyroxene Amphibole Ca-Rich Plagioclase
*Felsic.- rock with light-colored minerals. = feldspar + silica Remember what FELSIC rocks are made off! Made with: Quartz Potassium Feldspar Muscovite Na-rich Plagioclase *Intermediate.- Combination of both felsic and mafic. Terms: *Extrusive.- Igneous rock formed from lava. Rapid solidification. Small size. *Intrusive.- Crystallizes below earth s surface. Texture of Igneous Rocks: *Vesicular.- volcanic rock texture. open spaces, bubbles. *Phaneritic.- (coarse grained) Mineral grains Easily visible *Aphanitic.- (Fine grained) very small grains. *Porphyritic Texture.- mixed small and big grains. *Glassy.- No crystals visible. *Volcanic texture.- volcanic ash *Frothy texture.- More bubbles than rock
Igneous Rocks Classification Table Name Texture Minerals Present Mafic / Felsic Intrusive or Extrusive Picture Andesite Aphanitic Na-rich Plagioclase, Pyroxene Intermediate Extrusive Basalt Aphanitic Pyroxene Mafic Color Extrusive Diorite Phaneritic Feldspar, Pyroxene Quartz Intermidiate Intrusive Gabbro Phaneritic Ca-rich Plagioclase Mafic Intrusive Granite Phaneritic Feldspar, Quartz Felsic Intrusive Obsidian Glassy Silicon Dioxide *Felsic Extrusive Pumice Vesicular Potassium Feldspar Felsic Extrusive Rhyolite Aphanitic Quartz, Felspar Felsic Extrusive Vesicular Bassalt Frothy Pyroxene, olivine, amphibole Mafic Extrusive
Name Summary Q. Igneous rocks in the Wichita Mountains. - Wichita Mountains are rocky promontories and rounded hills made of red and black igneous rocks, light-colored sedimentary rocks, and boulder conglomerates. The Wichita Mountains were formed in four distinct geologic episodes. Granite 5. Sedimentary Rocks Type: Clastic *Clastic.- Comprised of pieces of other rocks (called clasts). If you can see clasts is the rock is clastic. 1. Clast size: Large-Gravel MediumLarge-Sand MediumSmall-Silt Small-Clay 2. Sorting: Well sorted (clasts of equal size) or poorly sorted (small and large clasts) 3. Roundness: Angular or rounded. *Chemical.- Non-clastic 1.- Mineral Composition: (eg. chert=quartz,; limestone=calcite; carbon= coal) 2.- Texture: Made of cystallized material (like chert) or shell fragments (like coquina) Sedimentary Rocks Classification Table CLASTIC Name Clast Size Sorting Roundness Picture Arkose >1/16mm Poorly sorted Angular
Name Clast Size Sorting Roundness Picture Breccia >2mm Poorly sorted Angular Conglomerate >2mm Well Sorted Angular Sandstone 1/16-2mm Well Sorted Rounded Shale <1/16mm Well Sorted Rounded Sedimentary Rocks Classification Table Chemical Name Mineral Comp Texture Picture Chert Quartz Crystallized material Coal Calcite Crystallized material Coquina Calcite Shell fragments Fossiliferous Limestone Calcite Shell fragments
Name Mineral Comp Texture Picture Limestone Calcite Crystallized material 6. Metamorphic Rocks 2 types: *Foliated metamorphic rocks.- such as gneiss, phyllite, schist and slate. Well defined, parallel alignment of minerals. Linear structures= FOLIATED *Non-foliated metamorphic rocks.- such as marble and quartzite which do not have any parallel structures. Name Foliated/ Non Foliated Parent Rock Picture Gneiss Foliated Schist Marble Non-foliated Limestone Phyllite Foliated Mudstone Quartzite Non-foliated Sandstone Schist Foliated Slate
Name Foliated/ Non Foliated Parent Rock Picture Slate Foliated Mudstone 6. Geologic Ages. *Doctrine of Uniformitarianism.- The present is the key to the past *Principle of original horizontality.- Because of this we know that sedimentary rocks that are not horizontal were moved from their horizontal position by later events, such as tilting. *Law of superposition.- states that, in undisturbed strata, newer layers will be placed over older layers. *Principle of inclusions.- If a rock contains fragments of another rock, the fragments must be older than the rock containing them. *Principle of Cross-cutting relationships.- Cross cutting rock is younger than the rock surrounding it. *Principle of fossil succession.- states that fossil organisms originate, coexist, and disappear from the geologic record in a definite sequential order. *Unconformities.- The relation between adjacent rock strata whose time of deposition was separated by a period of nondeposition or of erosion. Also learn: Rock Cycle
And the... 5 Principles of Stratigraphy: 1. Superposition 2. Original Horizontality 3. Inclusions 4. Cross-Cutting 5. Law of lateral continuity Note: The use of this guide is for studying purposes only.