Rodrigo Rivera-ReyesGEOL 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´ScaleF Fingernail= hardness of 2.5,P Penny= 3.5,I Iron Nail= 4.5G Glass= 5.5 andS 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 Conchoidal 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. *Phaneritic.- (coarse grained) Mineral grains Easily visible open spaces, bubbles.

*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 AphaniticNa-rich

Plagioclase, Pyroxene

Intermediate Extrusive

Basalt Aphanitic Pyroxene Mafic Color Extrusive

Diorite PhaneriticFeldspar, Pyroxene

QuartzIntermidiate 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 RocksType: 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 TableCLASTIC

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 TableChemical

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. Superposition2. Original Horizontality 3. Inclusions4. Cross-Cutting5. Law of lateral continuity

Note: The use of this guide is for studying purposes only.