GEOL 111 - Introductory Geology

Sections 01 and 02

Sections 03 and 04

Sections 05 and 06

Sections 07 and 08

Sections 09 and 10

Introductory Geology Sections 09 and 10

Mr. Doug Albach

Link to Chapter Outlines

Instructor: Douglas Albach

Prerequisite: There are no formal prerequisites for Geology 111, although it is expected that students will have completed at least a year of high school chemistry. 

Text: Monroe, J.S. and Wicander, R The Changing Earth: Exploring Geology and Evolution   3rd 

Classes:     Lectures are held on Monday and Wednesday from 6:00 – 7:15 p.m, in room 100 

  GEOLOGY 111 Class Schedule 

Course Grade 

Average of Monday quizzes (7of 8)       25 % 

Average of three in-class tests       30 % 

Comprehensive Final Exam       25 % 

Lab Grade         20 %

EARTH, Geologic Principles and History, Chernicoff, Fox & Tanner

Prepared by Douglas Albach

Chapter 1
Chapter 2
Chapter 3
Chapter 4
Chapter 5
Chapter 6
Chapter 7
Chapter 8
Chapter 9
Chapter 10

Chapter: 1  A First Look at Planet Earth

Introduction – Earthquakes and other natural disasters
   Loma Prieta October 17, 1989
   Northridge January 17, 1994
   Kobe Japan January 17, 1995

A. The Methods of Science and Geology – every effect has a cause
   1. The Scientific Method
       data ? hypothesis ? experiments ? theory ? scientific law

   2. The Development of  Geological Concepts
      a. Catastrophism – a series of immense worldwide upheavals, short total time
      b. Uniformitarianism – gradual changes over a long period of time 
           “The present is the key to the past”
      c. Modern synthesis

B. The Earth in Space “Goldilocks position”
   1. The Probable origin of the Sun and its Planets
      a. Big Bang ? H & He
      b. Galaxies, star formation, nuclear fusion, nova formation
      c. Solar nebula contracted into Sun and planets – light material swept out of area near 
          the Sun
      d. Planetesimal formation – planetary accretion
      e. Inner planets with heavy materials – outer planets: light 

   2. The Earth's Earliest History
      a. Solid, homogeneous body
      b. Heating: collision, compression, radiogenic ? melting
      c. Differentiation: Iron core, mantle, crust, ocean, air
      d. A glimpse of the Earth's Interior
         1 Crust – low-density, Si, O rich
         2 Mantle – denser rocks
             Lithosphere – upper 100 km, solid
             Asthenosphere – 100-350 Km, heat softened (flows)
         3 Core – liquid outer, solid inner
      e. The Origin of the Moon:  less dense, less iron
         1 Collision between Earth and Mars size planetesimal
         2 Moon formed from orbital debris
         3 Direct evidence long destroyed

C. Rocks and Geologic Time (deep time)
   1. Rock Types and the Rock Cycle
      a. Rock – naturally formed aggregate of one or more minerals
      b. Igneous – cooling and crystallization of molten material
      c. Sedimentary – preexisting rocks are broken down into fragments which accumulate 
          and become compacted and cemented
      d. Metamorphic – heat, pressure, or chemical reactions with circulating fluids change 
          the composition and structure

   2. Time and Geology
      a. Relative dating – spatial relationships
      b. Absolute dating – radioactivity
      c. Fossil sequence

D. Plate Tectonics – The New Paradigm
   1. Basic Plate Tectonic Concepts
      a. The outer portion of the Earth (lithosphere) is composed of large rigid units called 
          plates
      b. The plates move slowly in response to the flow of the heat-softened asthenosphere 
          beneath them
      c. Most of the world's large-scale geologic activity occurs at or near plate boundaries
      d. The interiors of plates are relatively quiet geologically

   2. Plate Movement and Boundaries
      a. Rifting and Divergent Plate Boundaries
         1 Rifting – pulling-apart of a plate 
         2 Divergence – plates separating with the formation of new oceanic crust at the 
            mid-ocean ridge (sea floor spreading)
      b. Plate Convergence and Subduction Boundaries
         1 Destruction of oceanic crust – subduction
         2 Continental collision – mountain formation
      c. Transform motion and Transform Plate Boundaries
           plates sliding past each other – San Andreas Fault

   3. The Driving Force Behind Plate Motion
      a. Convection cells within the asthenosphere
      b. Gravity of ridge and subduction zones

Chapter: 2  Minerals

Introduction – Value of Minerals
 Esthetic reasons – color, luster, symmetry
 Utilitarian reasons – tools, watches, talc,sulfur, fluorine, aluminum, kaolinite, 
   dietary nutrients 

A. The Chemistry of Minerals – naturally occurring inorganic solids consisting of atoms 
      in specific proportions and arrangements
      rocks – 
      element – 
      atom – 
      compound – 

   1. The Structure of Atoms
      a. Protons+neutrons=nucleus
      b. Electrons
      c. Number of protons=atomic mass (AMU), atomic number
      d. Isotopes – variable number of neutrons in nucleus
      e. Electrons in energy levels

   2. Bonding of Atoms – filling of energy levels (+ or -)
      a. Ionic bonding – gaining or losing electrons
      b. Covalent bonding – sharing electrons
      c. Metallic bonding – roaming electrons
      d. Intermolecular bonding – weak attachment of molecules
           hydrogen bonds – water
           van der Waals bonds – graphite

   3. Mineral Structure
      a. Crystal – crystal structure (internal)
      b. Mineraloids – lack specific structure, ex: glass

   4. Determinants of Mineral Formation
      a. Relative abundance of available elements
      b. Element interaction – size and packing
      c. Ionic substitution – ions of similar size and charge: Fe2+ ? Mg2+
      d. Polymorphism – same chemical composition but different crystal structure, 
          ex: diamond – graphite

B. Identification of Minerals – chemical & physical properties
   1. In the Field
      a. Color – sometimes diagnostic, sometimes not
      b. Luster – nature of reflected light
      c. Streak – color of powder
      d. Hardness – resistance to abrasion: Mohs scale
      e. Cleavage – tendency to break along distinct planes
      f. Fracture – type of breaking
      g. Smell and taste
      h. Effervescence – reaction to acid
      i. Crystal form

   2. In the Laboratory
      a. Specific gravity – density compared to water [heft]
      b. Fluorescence – uv light
      c. Electron probe
      d. X-ray diffraction

C. Some Common Rock-Forming Minerals
   1. Silicates – based on Silicon-Oxygen tetrahedron: SiO4, >90% of crust
      a. Independent tetrahedra
      b. Single Chains 
      c. Double chains 
      d. Sheet silicates
      e. Framework silicates

   2. Nonsilicates – 5% of Earth's crust
      a. Carbonates  (CO3)
      b. Oxides 
      c. Sulfides and sulfates
      d. Native elements

D. Gemstones
   1. Minerals that display particularly appealing color, luster or crystal form

   2. Generally large crystals
      a. Crystallization in voids
      b. Metamorphic activity: ruby, sapphires
      c. Deep crystallization: diamond

Chapter: 3  Igneous Processes and Igneous Rocks

Introduction
  Eruption of Hawai'ian volcanoes – formation of new rock
  Granite mountains – Sierra Nevada
  Igneous rocks – from liquid (fire)
  Investigation of underground processes after erosion
  Investigation by laboratory simulation

A. What is Magma?
   1. Magma – molten rock under Earth's surface 

   2. Lava – molten rock on or above Earth's surface

   3. Mixture of atoms and ions – form crystals when cooled

B. Classification of Igneous Rocks
   1. Igneous Textures – appearance of surface – depends on rate of magma cooling
      a. Phaneritic – visible crystals
         1 Slow cooling ? large crystals
         2 Intrusive or plutonic rocks
      b. Pegmatites – very large crystals, slow cooling from water rich magmas
      c. Aphanitic – not visible crystals
         1 Rapid cooling ? small crystals
         2 Extrusive or volcanic rocks
      d. Porphyritic – two crystal sizes, changing cooling rate – slow then faster
      e. Glassy – obsidian, quenching
      f. Glassy foam – pumice

   2. Igneous Compositions – relative abundance of O, Si, Al, Fe, Ca, Mg, Na, K, S and 
       others
     a. Ultramafic Igneous rocks: <40% SiO2 (silica)
         1 Ferromagnesian minerals – rich in Fe and Mg
         2 Peridotite  40-100% olivine
      b. Mafic Igneous rocks: 40-55% SiO2
         1 Basalt – aphanitic
         2 Gabbro – phaneritic 
      c. Intermediate Igneous rocks: 55-65% SiO2
         1 Andesite – aphanitic 
         2 Diorite – phaneritic
      d. Intermediate Igneous rocks: >65% SiO2
         1 Rhyolite – aphanitic 
         2 Granite – phaneritic

C. Igneous Rock Formation – complex process from a complex material
   1. The Creation of Magma
      a. Partial melting of rock
      b. Heat – formation, radioactivity, friction of plate motionGeothermal gradient  - 
          greatest from 50 – 250 km (zone of magma formation)
      c. Pressure – holds ions in place (raises melting point)
      d. Water – weakens the bonds

   2. The Crystallization of Magma
      a. Bowen's Reaction Series – sequence in which silicate minerals crystallize as 
          magma cools
         1 Discontinuous series – one mineral being transformed into another
         2 Continuous series – feldspar formation 
         3 leaving a melt (<10%) rich in Si, K, Al
      b. Cooling related changes in Magma
         1 Removal of crystals – settling, rising
         2 Fractional crystallization – formation of a new magma of a different composition
         3 Reaction with country rock
         4 Mixing of different magma bodies

D. Intrusive Rock Structures
   1. Plutons – bodies of intrusive rock
      a. Country rock – preexisting rock surrounding a pluton
      b. Concordant – parallel to layers of country rock
      c. Discordant – cut across layers of country rock

   2. Tabular Plutons – slab-like 
      a. Dike – discordant, around volcanic neck
      b. Sill – concordant

   3. Batholiths and Other large Plutons
      a. Laccolith – dome shaped concordant pluton, flat bottom
      b. Lopolith – saucer shaped, sagging downward
      c. Batholith – massive discordant plutons, >100 km2 surface area

E. Plate Tectonics and Igneous Rock – 
   1. Igneous rock distribution
      a. Plutonic structures – convergent or divergent plate boundaries
      b. Dikes and sills – divergent or rifting zones
      c. Granite batholiths – near oceanic subduction zones 

   2. Basalts and Gabbros – associated with oceanic crust
      a. Basalts – most abundant igneous rocks, highly fluid lava
      b. Mid-ocean ridge basalts – 65% of Earth's surface
      c. Ocean island basalts – associated with “hot spots”

   3. Andesites and Diorites
      a. Along subduction margins
      b. Andesite line – pacific rim
      c. partial melting of descending plate and interaction with surrounding rock

   4. Rhyolites and Granites – only on continental crust
      a. Partial melting of intermediate rocks
      b. High viscosity magma – cool at depth as granite

F. Igneous Rocks on the Moon
   1. Little or no water, no plate activity

   2. Old cratered highlands – anorthosite  4.0-4.5 BY

   3. Younger maria – younger basalt flows 3.8-4.0 BY from meteor impact

G. The Economic Value of Igneous Rocks
   1. Gemstones and precious metals, base metals

   2. Crushed stone, cut stone

Chapter: 4  Volcanoes and Volcanism

Introduction - volcanism
 Krakatoa August 27, 1883 ? ocean waves, 36,000-100,000 dead
 ~600 volcanoes erupted last 2,000 years
 Breathtaking scenery

A. The Nature and Origin of Volcanoes – a window on Earth's interior,
     origin of atmosphere, energy source
   1. Volcano Status
      a. Active – current or recent eruption
      b. Dormant – no recent eruption but possible
      c. Extinct – no recent eruption and not likely

   2. The Causes of Volcanism
      a. Gas in Volcanic magma – 1-9%, H2O, CO2, N2, SO2, Cl
         1 Comes out of solution as pressure decreases
         2 Concentrated near top of rising magma
         3 Vent clearing ? sudden release ? explosive eruption
         4 Later eruption much quieter
      b. Magma viscosity
         1 Decreases with heat and increases with SiO2 content
         2 Felsic magma generally cooler, high viscosity, more explosive
         3 Mafic hotter, lower viscosity, gas readily escapes

B. The Products of Volcanism – wide variety
   1. Types of Lava Flows
      a. Basaltic lava: pahoehoe-ropy, a'a-rough fragments
         1 Vesicles – bubbles ? scoria
         2 Basaltic columns
         3 Lava tubes
         4 Pillow structure – underwater eruption
      b. Andesitic and Rhyolitic Lavas
         1 Andesitic – flows and explosive eruptions
         2 Rhyolitic – explosive eruptions, no flows, pumice-glassy froth

   2. Pyroclastics – eruptive fragments
      a. Tephra – air cooled fragments
         1 Volcanic dust – long life in the atmosphere
         2 Volcanic ash - <2mm
         3 Cinders (lapelli) 2-64 mm
         4 Bombs >64mm, air cooled, streamlined
      b. Pyroclastic flows – nuée ardente ? welded tuff
      c. Volcanic mudflows – lahar, mixture of water and ash

C. Eruptive Styles and Associated Landforms
     Volcanic cone – mountain
     Volcanic crater – depression
      Caldera – large depression 

   1. Effusive Eruptions – quiet, non-explosive
      a. Central-vent eruptions ? shield volcano, flank eruption
      b. Fissure eruptions ? lava plateaus or flood basalts
      c. Submarine eruptions ? pillow structures, steam explosions

   2. Pyroclastic Eruptions – viscous, gas-rich magmas
      a. Volcanic dome 
      b. Ash-flow eruptions – ring fractures from domal uplift result in explosive release 
           and caldera formation: Yellowstone, Mammoth Lakes, CA
      c. Types of pyroclastic Volcanic cones
         1 Composite cone (stratovolcano) – alternating layers of lava and pyroclastics – 
            Fuji, Rainier, Shasta
         2 Pyroclastic cones (cinder cones) – loose pyroclastic material

D. Plate Tectonics and Volcanism
   1. 80% of volcanoes surround Pacific basin – subduction zones

   2. 15% in Mediterranean and Caribbean seas

   3. Divergent plate boundaries
      a. Mid-oceanic ridge
      b. Stretched continental crust – rift zones, Basin & Range

  4. Hot spots

E. Coping with Volcanic Hazards – control not likely, only prediction
   1. Volcanic hazards
      a. Cascade volcanoes: Mt Rainier-Seattle
      b. Valles caldera – Santa Fe, NM (incipient rift?)

   2. Defense Plans
      a. Volcanic zoning – set aside risk areas
      b. Diverting flows – bombs, water, dams

   3. Prediction Volcanisms
      a. Assessment of volcanic activity
      b. Detailed analysis after eruptive activity begins Earthquakes, mountain inflation, 
          gas vents, temperature
      c. Tiltmeters
      d. Harmonic tremors

F. Extraterrestrial Volcanism
   1. Lunar maria from meteorite strikes

   2. Martian crust – Olympus Mons

   3. Venus – large shield volcanoes, possible plate activity

   4. Io (Jupiter) – sulfur volcanoes

   5. Triton (Neptune)

Chapter: 5  Weathering: The Breakdown of Rocks

Introduction
  Weathering creates many spectacular landforms
  Erosion – the process by which gravity, moving water, wind, or ice transports pieces of 
     rock and deposits them elsewhere
  Sediment – loose, fragmented surface material
  Forms soil and tears down our constructions

A. Weathering Processes
   1. Mechanical Weathering – breaks a rock into smaller pieces but does not change its 
       chemical makeup
      a. Renders rocks more susceptible of chemical weathering by increasing surface area
      b. Frost wedging – repeated freeze-thaw cycles in fractured rock
      c. Crystal growth – salt from evaporating water
      d. Thermal expansion and contraction – heating and cooling of surface mineral grains
      e. Mechanical exfoliation – expansion due to release of external pressure
      f. Root wedging
      g. Animal activities
      h. Abrasion

   2. Chemical Weathering – changes the chemical composition (decomposes) of minerals 
       and rocks
      a. Dissolution – NaCl, Carbonic acid (H2CO3)
      b. Oxidation – mineral's ions combine with oxygen ions
           ex: iron bearing minerals – pyrite ? rust
      c. Hydrolysis – H+ or OH- ions from water molecules displace other ions from a 
          mineral's structure: feldspars ? clays

 3. Factors That Influence Chemical Weathering
      a. Climate – heat accelerates all chemical reactions, water facilitates chemical activity
      b. Living organisms – burrowing, organic acids
      c. Time – duration of exposure 
      d. Mineral composition – chemical stability determines rate of weathering 
          (same order as Bowen's series)

   4. Products of Chemical Weathering
      a. Clay minerals – several types from various minerals
         Feldspars ? kaolin
         Micas & amphiboles ? smectite
         Drilling mud, bricks, cement, paper
      b. Metal ores – weathering of more complex minerals
          Feldspars ? bauxite
      c. Rounded boulders – spheroidal weathering

B. Soils and Soil Formation
   1. Regolith – broken down rock material + organic material ? soil

   2. Influences on Soil Formation
      a. Parent material – supplies materials for soil
      b. Climate – moisture & temperature and organic activity
      c. Topography – availability of water, accumulation of materials
      d. Vegetation – produces ions involved in chemical weathering reactions 
      e. Time – balance of formation vs. destruction

   3. Typical Soil Structure
      a. Soil horizons
         O – humus
         A – humus + inorganics
         E – eluviated horizon (materials removed)
         B – illuviated horizon (materials added)
         C – weathered parent material
      b. Soil profile – combinations of horizons

   4. Classifying Soils
      a. Wide variety of soil types
      b. Soil taxonomy – classifications

C. Weathering in Extraterrestrial Environments
   1. Moon – physical weathering by meteorite strike

   2. Venus – high CO2, no water, thermal expansion and contraction

   3. Mars – oxidation, meteorite fall

Chapter: 6 Sedimentation and Sedimentary Rocks

Introduction 
  Sediment – unconsolidated material that accumulates at Earth's surface: 
     weathering products, chemical precipitates
  Sedimentary rock – thin covering: 5% of outer 15 km, 75% of surface
  Source of fossil fuels and some metallic ores: Fe, Al
  Clues to ancient environments and events

A. The origins of Sedimentary Rocks – detrital (most common) and chemical sediments
   1. Sediment Transport and Texture – gravity movement
      a. Grain size – decreases with distance from source
         1 Abrasion during transport – varies by minerals and transport medium
         2 Sorting – results from energy level and carrying capacity of transporting medium: 
            well or poorly sorted
      b. Grain shape – angular or rounded depending on transport medium, 
          mineral hardness, fragment size
   2. Sedimentary Structures – clues to depositional environment
      a. Bedding – stratification
         1 Bedding plane – change in texture
         2 Graded bedding – coarse ? fine: turbidity currents
         3 Cross beds – angled to underlying beds: dune forms
      b. Surface sedimentary features 
         1 Ripple marks – current or wave action
         2 Mud cracks – drying of clays
   3. Lithification: Turning Sediment into Sedimentary Rocks
      a. Compaction – decrease in volume by pressure of overlying sediments
      b. Cementation – deposition of mineral material by circulating fluids: CaCO3, SiO2, 
          Fe compounds
          sediments+cement?clastic sedimentary testure
      c. Recrystallization – from increased heat and pressure, common with CaCO3

B. Classifying Sedimentary Rocks 
   1. Detrital Sedimentary Rocks (clastic) – Wentworth scale
      a. Mudstones <0.004mm – low energy environments, shale from compaction and
          ordering of flat minerals
      b. Siltstones 0.004-0.063mm
      c. Sandstones – 0.064-2.0mm
         1 Quartz arenite >90% quartz: white, well sorted: long transportation
         2 Arkose >25% feldspar: pinkish color, poor sorting: deposition close to source
         3 Graywacke – multiple grain types, poorly sorted, gray to green: rapid deposition
      d. Conglomerates and breccias >2mm
         1 Conglomerates – rounded fragments, some transportation
         2 Breccia – angular fragments, no transportation

   2. Chemical Sedimentary Rocks
      a. Inorganic chemical sedimentary rocks – precipitated from solution
         1 Inorganic limestone – change in physical conditions
            carbonate mud, cave deposits, tufa
         2 Dolostone – replacement of ~50% of Ca in calcite with Mg during lithification: 
            associated with salt deposits
         3 Evaporites – concentration of salts in water by evaporation: gypsum, halite
         4 Chert – inorganic silica precipitation or concentration
      b. Biogenic chemical sedimentary rocks
         1 Biogenic limestones – shell fragments: shallow, warm water
         2 Biogenic chert – layered chert, diatom shell accumulation
         3 Coal – accumulation of plant material: swamps
             peat?lignite?bituminous?anthracite 

C. “Reading” Sedimentary Rocks
   1. Sediment Deposition Environments
      a. Continental: river, lake, desert, glacier, cave
          wide variety of energy levels
          Alluvial fans – Cg at base of mountains or faults
      b. Marine environments
         1 Shallow water – land derived and photic zone sediments
         2 Deep-marine – settling of microscopic materials, turbidite deposition
         3 Transitional (coastal) environments: 
            beaches, tidal flats, estuaries, deltas, lagoons

   2. Sedimentary Facies (aspect) – the unique set of characteristics that distinguishes a 
       sedimentary rock deposit from others from different environmental conditions, a rock 
       with particular characteristics: vertical vs horizontal succession of facies

   3. Sedimentary Rocks and Plate Tectonics
      a. Recent rifting ? alluvial fans
      b. Transform boundaries ? rapid sedimentation
      c. Convergence ? mountains and volcanoes
      d. Evidence of past events – Blue Ridge

Chapter: 7 Metamorphism and Metamorphic Rocks

  Metamorphic rocks – High temperature and pressure solid-state changes
  Below sedimentary zone, above melting zone
  Generally underlie sedimentary rocks, exposed in continental interiors and mountains
  Metamorphism is an ongoing process

A. Conditions Promoting Metamorphism
  Rocks and their constituent minerals are most stable in the environment in which they 
   form
   1. Heat  - 200?C + occurs below 10 km; magmatic intrusions

   2. Pressure – 1 kilobar 3 km beneath surface
      a. Lithostatic of confining pressure – increase with depth
      b. Directed pressure – Greater in one direction ? foliation

   3. Circulating Fluids – medium for migration of ions

B. Types of metamorphism
   1. Contact Metamorphism – heating by nearby magma or fluids from magma
        ? metamorphic aureole

   2. Regional Metamorphism – large area
      a. Burial metamorphism - >10km of sediment, generally non-foliated
      b. Dynamothermal – converging continental plate collision directed stress, cores of 
          mountain ranges

   3. Other Tyupes of Metamorphism
      a. Hydrothermal – hot water, mid-oceanic ridges
      b. Fault metamorphism – grinding and frictional heating
      c. Shock metamorphism – meteor strikes
      d. Pyrometamorphism – lightning

C. Common Metamorphic Rocks – foliated or nonfoliated
   1. Foliated metamorphic Rocks Derived from Shales or mudstones
      a. Slate – gray and flat: rock cleavage from orientation of micas
      b. Phyllite – shiny from greater percent or mica
      c. Shist – glittery from coarse grained mica
      d. Gneiss – separation of minerals into bands (metamorphic differentiation)
      e. Migmatite – partial melting

   2. Foliated metamorphic Rocks Derived from igneous Rocks
      a. Basalt ? Greenschist – chlorite or epidote 
      b. Granite ? quartz rich gneiss

   3. Nonfoliated Metamorphic Rocks – recrystallization
      a. Limestone or dolomite ? marble
      b. Sandstone ? quartzite
      c. [Basalt ? greenstone]
      d. Hornfels – dehydration by thermal 

D. Metamorphic Grade and Index Minerals
   1. Metamorphic grade
      a. Low-grade – retain original character: bedding, fossils
      b. High-grade – lack all original structures

   2. Metamorphic index minerals 
      a. Indicators of specific environments
      b. Mineral zones – multiple for a particular event

E. Metamorphic Facies and Plate Tectonics
   1. Indicates the specific temperature and pressure conditions 

   2. Presence of a certain set of minerals

   3. Differing temperatures resulting from descending plate

   4. Most regional metamorphism results from continental convergence

   5. Most contact metamorphism results from magma from descending plates

F. Metamorphic Rocks in Daily Life
   1. Practical Applications of Metamorphic Rocks
      a. Building exteriors and foundations
      b. Decorative stones – serpentinite, marble
      c. Soapstone – sculpture and lab counters
      d. Talc, asbestos
      e. Gems and abrasives – garnet 

   2. Potential Hazards from Metamorphic Rocks – Foliation can weaken slopes

Chapter: 8 Telling Time Geologically

Introduction
  Geochronology – Earth time
  Historical Geology – origin and evolution of Earth's life forms and geologic structures

A. Geologic Time in Perspective
   1. Major events
      a. 4,600,000,000 years vs. 70 years
      b. Oldest rocks 3.96 by, oldest life 3.77 by
      c. Complex life ± 600my, fish 510my, land plants 438my, Dinosaurs 245my

   2. Relative dating 

   3. Absolute dating

B. Determining Relative Age
   1. Principles Underlying Relative Dating
      a. Uniformitarianism – Geologic processes taking place in the present operated 
          similarly in the past
      b. Original horizontality  - laid down horizontal
      c. Superposition – older below younger
      d. Cross-cutting relationships – younger crosses (cuts) older
      e. Inclusions – younger includes fragments of older
      f. Fossils and faunal succession – over time the organisms of Earth have changed in a 
         definite order and this progression is refledted in the fossil record
      g. Index fossils – fossils with wide distribution and narrow time span

2. Unconformities – gaps in the geologic record
      a. Nonconformity – sedimentary rock over igneous or metamorphic rock
      b. Angular unconformity – sedimentary rock over tilted and eroded sedimentary rock
      c. Disconformity – parallel layers of sedimentary rock with a gap in time

   3. Correlation – Determination that two layers of rock in different locations are 
       equivalent 
      a. Similarities in fossil assembleges or index fossils
      b. Presence of key beds – a distinctive stratum that appears at several locations

C. Determining Absolute Age
   1. Radiometric Dating – through radioactive isotopes
      a. Relative proportions of parent isotope and daughter isotope
      b. Radioactive decay – half-life
      c. Factors affecting radiometric-dating results
         1 Origin of the mineral crystal
         2 Age and condition of material
         3 Duration of half-life
         4 [Loss of parent or daughter isotopes]
         5 Best to use several tests
      d. Isotopes used in radiometricdating
         1 See table 8-1
         2 Carbon-14, half-life of 5,730 years, atmospheric origin

   2. Other Absolute-Dating Techniques
      a. Fission-track dating – counting the tracks of high-speed particles in radioactive 
          minerals
      b. Dendrochronology – tree ring matching: up to 9,000yr
      c. Varves – annual sediment layers, usually from ice
      d. Lichen: lichenometry – size and rate of growth yield time of exposure

   3. Combining Absolute Dating with Relative Dating – absolute dates from radioactive 
       sources with relative dates to fill in the details in between

   4. The Age of the Earth
      a. Oldest Earth rocks 3.96 by
      b. Oldest Moon rocks 4.53 by
      c. Oldest meteorites 4.6 by

Chapter: 9 Folds, Faults and Mountains

Introduction
  Some mountain ranges are growing visibly, others being Eroded
  Almost all related to plate tectonics

A. Stressing and Straining Rocks
      Stress – applied torce
      Compression – converging stress  ??
      Tension – diverging stress   ?
      Shearing stress – opposite and parallel stress  ?
      Strain – change in shape under stress
   1. Types of Deformation
      a. Elastic deformation – deformation and rebound
      b. Brittle failure – fracture under stress
      c. Plastic deformation – bending under stress

   2. Deformed Rocks in the Field
      a. Strike – compass direction of horizontal line on tilted surface    ?
      b. Dip – angle and direction of inclination   ?

B. Folds – bends in rock layers
   1. Synclines and Anticlines
      a. Synclines – downward folds: youngest in center  ?
      b. Anticlines – upward folds: oldest in center   ?
      c. Axial plane – center of fold, 
      d. Axis – line along axial plane
      e. Symmetrical – vertical axial plane
      d. Asymmetrical – tilted axial plane
      e. Overturned – one limb is reversed
      f. Recumbent – horizontal axial plane
      g. plunging folds – dipping axis

   2. Domes and Basins
      a. Dome – down folded limbs of a circular structure: oldest in center
      b. Basin – up folded limbs of a circular structure: youngest in center 

C. Faults
      Fracture – crack in rock without displacement
      Fault – fracture with displacement
      Fault plane – surface of fracture
      Fault block – rock masses between fault planes

   1. Types of Faults
      a. Strike-slip faults – horizontal displacement
      b. Dip-slip faults – tilted displacement, hanging wall ? foot wall
      c. Normal fault  – foot wall moves downward
      d. Reverse fault – foot wall moves upward
      e. Thrust fault – low angle reverse fault

   2. Plate Tectonics and Faulting
      a. Normal faulting – tension from divergent boundaries
      b. Reverse faulting – compression from convergent boundaries
      c. Strike-slip faulting – transform boundaries

D. Building Mountains
      Ranges: Blue Ridge

      Systems: Appalachian

      Some mountain ranges are young and growing visibly, others are old and being 
       eroded, others totally eroded

   1. Types and processes of Mountain Building :orogenesis
      a. Fold and thrust – continental plate collision intruded and metamorphosed by large 
          plutons
      b. Fault-block – tensional bounded by normal faults, horsts and graben
                                                                                               ?             ?
      c. Upwarped – large area gently bent into broad regional uplifts: Adirondack

   2. Mountain Building on Our Planetary Neighbors
      a. Mountains of the Moon and Mars
         1 Accumulation of impact debris
         2 Volcanic
      b. Mountains of Venus – volcanic and possible plate tectonics

Chapter: 10 Earthquakes and the Earth's Interior

Introduction
  Jan 17,1995 Kobe Japan, Richter 7.2, 5,000 dead, 29,000 injured
  December 1995 Mexico offshore
  Loma Prieta 1989
  North Ridge 1994

A. Causes and Characteristics of Earthquakes
  Earthquake – a trembling of the ground caused by a sudden release of energy in 
    underground rocks
  Focus – location of beginning of rupture
  Epicenter – location on surface above 

   1. Seismic Waves – energy waves within the Earth
      a. Body waves – through the interior of the Earth
         1 P-waves – compressional, fastest 6-7 kps
         2 S-waves – shearing 3.5 kps
      b. Surface Waves – upper few km, 2.5 kps
         1 Side-to-side wipping motion
         2 Rolling motion

   2. Measuring Earthquake Strength
      a. Mercalli Intensity Scale – based on damage to structures
      b. The Modern Seismograph – instrument to measure earthquake waves on a 
          seismogram
      c. The Richter Scale – magnitude of earthquakes measured by seismographs, 
          logarithmic scale, limitations
      d. Moment-magnitude scale – energy released at rock rupture related to seismic 
          moment

   3. Locating and Earthquake's Epicenter – triangulation from distance measured by P-S 
       wave arrivals

B. The Effects of Earthquakes
   1. Ground Displacements
      a. Horizontal displacements
      b. Fault scarps
      c. Large scale displacement

   2. Landslides and Liquifaction – breaking down clay layers into sluries

   3. Seiches – Water sloshing in a lake basin

   4. Tsunami – Seismic sea waves from undersea displacement

   5. Fires – Ruptured gas lines, broken water mains

C. The World's Principle Earthquake Zones
   1. Earthquake Zones at Plate Boundaries
      a. 80% associated with Pacific Rim
      b. Most of the rest – Greece-Himalayas
      c. Divergent zones, continental rifts – shallow earthquakes
      d. Subduction zones – shallow ? deep (700km) Benioff-Waditi zone

   2. Intraplate Earthquakes
      a. Generally shallow (<50km)
      b. Effective earthquake transmission
      c. Activity on old faults

D. Coping with the Threat of Earthquakes
   1. Construction in Earthquake-Prone Regions
      a. Light, flexible materials move with the Earth
      b. Buildings well connected
      c. Lack of heavy decorative trim
      d. Armenia vs Loma Prieta
      e. Building on stable ground

   2. Earthquake Prediction: The Best Defense
      a. Statistics: frequency and magnitude of past events
      b. Excavation and dating of fault traces
      c. Building code 
      d. Long-Term Prediction
         1 Tectonic creep – frequent small motion
         2 Seismic gaps – earthquake free zones along faults
      e. Short-Term Prediction (precursers)
         1 Dilatency – expansion of rock by multiple minute cracks in response to stress
         2 Foreshocks – preliminary shocks
         3 Animal activity
         4 Inexact science at best

E. Investigating the Earth's Interior – variable speed of seismic waves through Earth's 
    materials
   1. The Behavior of Seismic Waves
      a. P waves travel through any medium
      b. S waves travel only through solids
      c. Waves reflect off boundaries at shallow angles
      d. Waver refract (bend) when passing through boundaries

   2. The Crust – Silicate rich igneous rocks
      a. Continental crust – 70-20km thick, more felsic above
      b. Oceanic crust – formed at spreading centers
         1 Sediment 200m average
         2 Pillow Basalt 2km
         3 Gabbro 6km
      c. The Crust-Mantle Boundary – Seismic discontinuity discovered by 
          Mohorovi?i? (Moho)

   3. The Mantle – 80% of Earth's volume
      a. The Upper Mantle – mostly peridotite
         1 Brittle to 100km + crust ? lithosphere
         2 100-350km is low velocity zone: P-waves decrease then increase (asthensphere)
      b. The Lower Mantle 700-2900km – solid with a steady increase in density and 
          velocity
      c. The Mantle-Core Boundary – P-waves decrease and S-waves disappear, 
          significant inverted landscape

   4. The Core – iron 2900-6370km
      a. The Liquid Outer Core
         1 Results in P-wave shadow zone 103?-143?
         2 S-wave shadow zone beyond 103?
      b. The Solid Inner Core – Faster P-waves 143?-180?