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CLEMSON / Geology / GEOL 1010 / What is the history of geology?

What is the history of geology?

What is the history of geology?

Description

School: Clemson University
Department: Geology
Course: Physical Geology
Professor: Alan coulson
Term: Fall 2015
Tags: Physical Geology and Geology
Cost: 50
Name: Physical Geology EXAM 1 Study Guide
Description: This study guide covers all of the material that will be covered on Exam #1 of Alan B. Coulson's Geology 1010 class
Uploaded: 01/29/2016
11 Pages 88 Views 13 Unlocks
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GEOL 1010 ­ Dr. Coulson ­ TEST 1 STUDY GUIDE


What is the history of geology?



Highlight = Important Principle Highlight = Key Term

Lecture 1​­ Intro to Science and Earth’s Formation

What is Science?

­ Relies on using facts and principles

­ Fact ­ ​repeatedly demonstrated to be true

­ Principle ­ true ‘ides’ (unlike facts, which are true ‘statements’)

­ Scientific Method:

1. Observation ­ noticing things (physical features, colors, etc.) Don't forget about the age old question of What is an economic growth?
We also discuss several other topics like What is minstrelsy?

2. Question ­ asking how, why, where, etc.

3. Hypothesis ­ an educated guess

a. MUST be testable and predictive

i. “Can I test it?”

ii. “Am I able to predict the outcome?”


What is a nebula?



b. Does it pass the “if­then” statement test?

i. Doesn’t HAVE to, but it is a safe and widely accepted format

ii. ex: “IF t​his happens, THEN​this is true.”

c. Can write a hypothesis for past and future events

d. Can be an easy or difficult hypothesis: as long as it is testable and predictive, then it works!

***FOR TEST: Know how to identify a good/bad hypothesis!!!***

4. Data ­ Collection of numbers, facts, observations, etc.

5. Evaluation ­ What does our data tell us? If you want to learn more check out What is the language of business?

a. Was our hypothesis correct?

i. More often than not, original hypothesis will be WRONG!!

­ Theory ­ a hypothesis that has stood up over time and tested to be true by other people ­ Law ­ a theory that has held up over time and has almost always been proven true ­ You MUST have scientific data to challenge scientific idea


What is the lower mantle of the earth?



­ ex: You can’t use psychology or religion to disprove a scientific idea

What is Geology?

­ Catastrophism ­ everything about earth is explained as a result of a catastrophe ­ ex: Noah’s flood caused certain animals to be in certain places

­ History of Geology:

­ James Hutton (Scottish) We also discuss several other topics like How do we measure nutrients?

­ wrote Theory of the Earth (1795)

­ Principle of Uniformitarianism ­ earth has behaved the same forever

(“Present is the key to the past”)

­ little changes can cause huge outcomes in the future

­ exact opposite of “catastrophism”

­ became cornerstone of Geology (replacing

catastrophism)

­ Actualism ­ says that Uniformitarianism is true most of the time, but everything happens at different speeds

­ takes into account asteroids, ice ages, etc.

­ meteors enter earth’s atmosphere at 40 km/s (90,000

mph)

How did the Earth Form?

­ 6 billion years ago (Ga), there was no solar system; just a nebula of Hydrogen atoms ­ Nebula ­ gas cloud in space

­ Nebular Hypothesis ­ best hypothesis to explain solar system formation

Step 1) Gravity ­ held clusters together and drew separate nebulas together

Step 2) Solar Disk Model ­ the massive clusters that were formed by gravity began to flatten out

Step 3) Protostar ­ prototype star forms in center and gains heat (6 Ga) We also discuss several other topics like What are the two different parts of formed elements?

Step 4) Fusion ­ atoms surrounding protostar fuse with it, and it becomes a full­blown star (or sun)

­ Planetary Accretion (4.5 Ga) ­ formation of planets is explained by rocks, dust, dirt, etc. fusing together over time

­ Planetary Accretion STILL HAPPENS TODAY

­ Theia Impact ­ Earth (in its earlier years) ran into another planet, Theia

1. Lunar formation ­ the moon was finally formed

2. molten planet ­ everything on earth turned to molten

a. density ­ measures capacity

3. Density Stratification ­ separation of layers of earth (core, mantle, etc.)

­ How old is Earth?

­ 4.5 Ga (billion years ago)

Lecture 2​­ Plate Tectonics

**​Geology in the News: ​Satellite data is giving geologists new info on why Greenland ice caps are melting

Layers of the Earth

­ 4 Chemical Layers ­ each with different chemistry (aka “composition”) (know both names) 1. Crust ­ lighter, lower density elements; lots of oxygen in this layer Don't forget about the age old question of What is the history of psychology?

a. 8­45 km thick

b. continental crust ­ found under continents

c. oceanic crust ­ slightly more dense than continental crust; found under ocean

2. Mantle ­ 45­2900 km thick; denser elements

3. Outer core ­ high iron/nickel elements, but some other ones too

4. Inner core ­ completely iron/nickel

­ 5 Physical Layers (aka “mechanical”)

1. Lithosphere ­ very brittle; thicker than the chemical layer “crust”

2. Athenosphere ­ part of the mantle; malleable material (NOT the same as mantle)

3. Lower mantle or “Mesosphere” ­ brittle material

4. Outer core ­ very malleable/fluid material

5. Inner core ­ very brittle material

Chemical/Compositional Layers Physical Layers

**NOTE:​Physical Layers and Chemical Layer are NOT the same thing!!**

Basics of Tectonics

­ Unifying theory of geology developed in the 1960s

­ The Lithosphere (first of physical layers) is divided into pieces, or plates

­ About a dozen major plates, none of which correspond to a specific continent

Developing Plate Tectonic Theory

­ Alfred Wegener’s Continental Drift 

­ Noticed that the continents fit together like a puzzle, and he began his research about the phenomenon

­ Data supporting Continental Drift:

­ Mountain chains

­ Fossils

­ Animal Species

­ Very few people believe in this theory

­ Wegener was unable to answer “how?” when people asked

­ 1940s ­ major research in oceans takes place

­ Submarines used for investigating these depp, dark places

­ Mid Ocean Ridge (MOR) ­ new discoveries made

­ Magnetic Reversals ­ Positive/Negative magnetic readings were

reversed in some areas

­ Age Anomalies of Seafloor Rocks ­ age of rocks would get older as

moving away from the ridge

­ Seafloor Spreading ­ moving of seafloor away from the center to make room for new rock formation

­ Explained magnetic and age anomalies

­ Finally explained “how” continental drift worked

­ How plates move ­ all four of these ways work together and simultaneously

1. Convection ­ material circulates between hot/cold and thus, new material is formed and pushes previous material away

2. Ridge Push Model Theory ­ magma comes up through the crust and pushes material away 3. Slab Pull Model ­ plates are pulled down into the earth

4. Slab Suction ­ as plates are pulled down, others near it are sucked into the earth with it ­ Plates move at about 3 in. per year on average

Plate Boundaries*

*​NOTE: ​Subduction, Collision, Rift Valley, etc. are ALL types of boundaries ­ 3 things can happen where two plates meet:

1. They can pull away from each other (divergent margins)

a. In Oceanic Areas (ex: Mid Ocean Ridge)

i. Causes formation of volcanoes

b. Continental Areas

i. Causes Rift Valley formation; some volcanoes

2. They can run into each other (convergent margins)

a. Subduction ­ ocean­continental collision

i. Volcanic activity and earthquakes

ii. Oceanic Plate always gets pushed downward

b. Collision ­ continent­continent collision

i. Mountain Range formation

3. They can slide past each other (Transform Margin)

a. Lots of earthquakes

**Important Plates to Know: Nazca, North American, South American, Eurasian, Pacific** Lecture 3​­ Minerals and the Rock Cycle

**Geology in the News:​Seismic activity in the Pacific Northwest linked to subduction of Juan de Fuca plate

Materials and Rocks/Basic Chemistry

­ minerals used for many things other than rocks

­ in foods you eat, in products you use, etc.

­ used in building/construction

­ used to sell for lots of money (diamonds)

­ Atoms ­ contains nucleus (with neutrons and protons) and surrounding electrons ­ Atomic Number ­ tells us the number of protons in and atom

­ tells us what element the atom belongs to

­ you can change the number of electrons and neutrons, but NOT protons (without changing the entire element)

­ Earth’s crust is made up of different elements, but not many

­ almost 50% is oxygen, about 28% is silicon

What is a Mineral?

­ Must pass ALL 5 requirements:

1. Non­synthetic ­ must be formed in nature

2. inorganic ­ not living and do not have lipids proteins, etc

3. crystalline ­ molecules arranged in very organized, tight patterns

a. opposite of crystalline is amorphous, meaning without a tight pattern

4. solid ­ not liquid or gas

5. set chemical composition ­ able to write a chemical formula

a. some substitutions are ok, some substitutions have slightly different compositions

Mineral Properties

­ color ­ although easy to identify, some minerals have different colors

­ ex: a sample of Quartz could be blue while another sample of Quartz could be pink ­ streak ­ color of mineral when ground up

­ sometimes the streak can be a different color than the actual mineral

­ Hardness ­ how difficult is it to scratch or damage

­ Moh’s Scale ­ scale of 1­10 (1=soft, 10=hard)(1=Talc, 10=diamond)

­ Tools: fingernail (hardness of 2.5), pocket knife (hardness of 5), etc.

­ There can be a range of hardness, as well as a range of tools

­ Luster ­ how shiny/bright the mineral is

­ metallic ­ very shiny/reflects light

­ vitreous ­ glassy; some light passes through

­ silky, pearly, and more

­ Effervescence ­ the “Acid” Test ­ will the sample fizz when acid is added?

­ Crystal Formation ­ how crystals form (some form in cubes, some with sharp edges, etc.) ­ Most crystals are hard to identify unless in perfect condition

­ Breakage Pattern ­ how the mineral breaks

­ Fracture ­ no set pattern to the break

­ Cleavage ­ forms flat, smooth surfaces when broken

­ pay attention to HOW it broke (in which direction, at what angle, number

of faces)

­ Many other mineral properties as well, including taste, magnetism, odor, etc

Common Mineral Groups

­ depends on what anion (negatively charge particle) the mineral has

­ ***common test question: How do you classify a mineral? (answer: anions)

­ Sulfides (S) ­ sulfur atom as the anion (metal + anion)

­ Oxides (O) ­ oxygen atoms are anions (metal +anion)

­ Sulfides and Oxides are very desirable due to cost effectiveness

­ Sulfates (SO₄) ­ sulfur bonded to oxygen

­ used in construction (drywall), plasters (casts), etc.

­ Phosphates (PO₄) ­ not common, but important in fertilizers, bones, and teeth ­ Carbonates (CO₃) ­ found in invertebrates (corals, shells, etc.)

­ strong effervescence feature

­ Silicates (SiO₄) ­ tetrahedron geometry

­ Polymerization ­ combing tetrahedron together (by the oxygen atoms)

­ Types of Silicates:

1. island silicates ­ no polarization

2. chain silicates ­ form chains/strings of silicates

a. single chain or double chain

3. sheet silicates ­ expanding on 2D surface; layered structure

a. weak bonding; easy to peel off of one another

4. Framework silicates ­ encountered very often

The Rock Cycle

­ rocks ­ DIFFERENT THAN MINERALS!

­ minerals make up rocks

­ only 3 types of rocks:

­ differentiated by how they form (explained in the Rock Cycle)

1. Igneous Rocks ­ formed by cooling of magma (liquid, molten rock)

a. weathering ­ breaking down of rock

b. erosion ­ carrying of weathered rock to another location

c. deposition ­ placement of eroded sediments

2. Sedimentary Rock ­ formed by Lithification (building up of previously broken up rocks) 3. Metamorphic Rock ­ formed by Metamorphism (forming by replacing old minerals with new ones by high temperatures and high pressure)

a. increasing temp may cause forming of magma which restarts the cycle

**NOTE:​There can be shortcuts in the cycle! Metamorphic Rock can be broken down into sedimentary rock, igneous rock can become metamorphic rock by increasing temp/pressure, and sedimentary rock can be broken down again to become more sedimentary rock

Lecture 4​­ Igneous Rocks and Processes

**​Geology in the News:​21,000 homes in Flint, Michigan have lead contamination in drinking water Magma

­ Why do we care?

­ some activity can be hazardous, so we want to know more about it

­ igneous rocks are good for construction, as they are durable and easy to use

­ magma ­ liquid rock (low ground)

­ lava ­ same as magma but at high ground

­ How to create magma:

1. Temperature ­ rocks melting point is about 500/600 degrees

a. rocks made up of different minerals, each with their own melting points

b. partial melting ­ melting of rocks occurs gradually and at a range of temps. (because of different minerals present)

2. wet melting ­ presence of water causes lower melting point which leads to faster melting 3. Decompression Melting ­ less pressure = lower melting point

­ magma composition

­ gases (small amounts, dissolved)

­ important in volcanic eruptions

­ SiO₂(Silicon)

­ 3 main types of magma:

1. Basaltic Magma ­ most common magma on earth

a. generated in mantle

b. dry magma ­ less water than other magmas

c. 50% SiO₂(pretty low percentage)

d. over 1100 degrees C (relatively hot for magma)

e. can find this magma almost everywhere

2. Andesitic Magma 

a. found only in/around Pacific

i. Andesite Line and Ring of Fire

b. more understood after plate tectonic theory

i. subduction causes this odd magma

ii. Andesitic Magma forms at subduction zones (continental and oceanic

plates colliding)

c. 60% SiO₂

d. 1000 degrees C (relatively lower temp for magma)

e. relatively dry magma

3. Rhyolitic Magma 

a. cooler temp: 700­800 degree C

b. 70% SiO₂

c. wet magma (higher water content)

**STUDY TIP: Don’t try to memorize all 3 types and each detail; know HOW each one relates to each other (ex: higher SiO₂content, low/wet magma, etc.)

­ crystallization ­ freezing of magma to form igneous rock

­ partial freezing ­ freezes at a range of temps due to multiple minerals

­ equilibrium crystallization ­ everything in magma is frozen into the rock; identical chemical composition from liquid⟶solid

­ fractional crystallization ­ something is removed during freezing process; different chemical compositions from liquid⟶solid

­ as the minerals freeze, they form in a specific sequence

­ Bowens Reaction Series ­ diagram that shows how this works

­ Discontinuous Branch ­ goes from forming one kind of

mineral to forming another (left­hand branch)

­ Continuous Branch ­ plagioclase is calcium­ or

sodium­rich, based on temp (right­handed branch)

**Know order of minerals on the branches, and know the left­handed margin (temp bar)

Igneous Rocks

­ how to identify igneous rocks

­ Texture ­ how large mineral crystals are

­ Composition ­ what makes up to rock

­ 2 broad types:

1. Plutonic (aka Intrusive) ­ formed in low surface (not lava; only magma)

­ pluton ­ any large body of plutonic rock

­ dikes and sills ­ long/narrow

­ dikes oriented vertically

­ sills relatively parallel to ground

­ Laccolith ­ dome­shaped frozen magma

­ Batholith ­ large plutons with no particular shape

­ main characteristic: Large size

­ Mt. Rushmore is carved in Batholith

**Know how these look: common test Q is to identify pictures

­ Textures

­ Pegmatite (negmatite) ­ many relatively large crystals

­ Phaneritic ­ smaller crystals but still visible

­ Composition

­ could identify each mineral individually

­ color index ­ color can tell you composition (works most of time)

­ Felsic ­ lighter color (white, pink, red)

­ intermediate ­ equal mix of light/dark; grayish color

­ mafic ­ dark colors (black/brown)

­ ultramafic ­ green/yellow minerals

2. Volcanic (aka Extrusive) ­ formed above surface of earth

­ use textures/composition to determine

­ Texture:

­ porphyritic ­ some small some large crystals

­ forms due to rapid freezing process of this type of rock

­ Aphanitic ­ can’t see many crystals without magnification

­ glassy ­ looks and feels like glassy

­ example of how color index can fail you

­ vesicular ­ many holes and openings in the rock

­ holes form because of last­minute gas bubbles popping while rock is

freezing

**Geology in the News​: volcanic glass ‘egg’ found after Kilauea eruption last week (never seen before) Volcanoes

­ the US does NOT have to worry about volcanoes

­ Japan and Indonesia are the only countries with more volcanoes than the US

­ Active US volcanoes

­ Hawaii: 7

­ Alaska: 41

­ Other 48 states: 20

­ Case Study: Krakatoa 

­ Indonesia island volcano

­ Aug. 23, 1883

­ 200 million tons TNT (13,000x amount of Hiroshima atomic bond)

­ air pressure waves circled the globe in 5 days (all the way to the English Channel) ­ over 30,000 languages extinct as a result

­ ⅔ of island destroyed; new volcano built since then

­ Volcano Explosivity Index (VEI) ­ measures intensity of volcano/eruption

­ many smaller eruptions

­ Types of eruptions:

1. explosive ­ large explosion

2. non­explosive ­ steady lava flow

­ Viscosity ­ measures thickness/ability to flow (low=flows fluidly)(high=flows slowly) ­ controlled by 2 things

1. Temperature ­ increases in temp = lower viscosity

2. Silica content ­ increases in Silica = higher viscosity

­ controls gas content

­ higher viscosity lets less gas to flow through it; this causes pressure

build up and leads to explosive eruptions

­ more gas retained = bigger explosion

­ non­explosive features:

1. Pahoehoe ­ first stage of cooling

­ soft look

­ cooling on top but still hot and in motion underneath

2. Aa ­ next stage of cooling

­ lava looks more brittle, uneven, and broken

­ there can still be some small bits of gas in them (vesicles)

­ speed of flow: “faster” lava ­ about 16km/hr (10mph)

­ explosive features:

­ more hazards beyond lava

­ Lahar ­ mudslide of volcano eruptions

­ faster than lava flow, so more dangerous

­ Pyroclasts ­ solid objects being ejected

­ divided by size

­ Bombs: >64mm

­ Lapilli: 2mm­64mm

­ Ash: <2mm

­ Very dangerous: can fall in high amounts

­ can build up and weigh down roofs

­ can be sucked up into engines

­ can be inhaled and destroy lungs

­ not something that has been burned up: just like

bombs and lapilli, ash is made up of solids

­ Pyroclastic Flow ­ gas overflow that flows down sides of volcanoes

­ not easy to escape from

­ Types of Volcanoes: 

1. Shield Volcano ­ gentle slope, shield shape (hence the name)

a. very common

b. Basaltic magma (explains shape of volcano)

2. Tephra (Cinder) Cone ­ steeper slope

­ smaller size

­ more solid debris (pyroclasts)

3. Stratocones ­ aka composite volcano, stratovolcano

­ more explosive eruptions

­ high viscosity

­ steeper landscape; stereotypical shape

­ Supervolcanic Eruptions ­ large enough to change climate on global scale

­ Tambora (1815) 100km^3 ejecta

­ in Indonesia

­ changed climate patterns over a year later in England, US, Ireland, etc

­ caused drastically cooler temps

­ Yellowstone Huckleberry Ridge 

­ 2 million years ago, 2500 km^3 ejecta

­ covered almost half of the US

­ not even the largest eruption in history

­ Hot Spots ­ typically where two plates meet

­ The Hawaiin Problem ­ Hawaii and all of its volcanoes are in the center of the Pacific Plate

­ “Hot Spot” is where there is magma that is coming up from underneath

­ Hawaiin Problem explained moving of the plate caused formation of

new volcanoes which, as the plate continued, became dormant and able to live

on

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