GENERAL GEOLOGY Fall Chapter 8: Time and Geology. Partial Examination II Study Guide Dr. Glen S. Mattioli

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1 GENERAL GEOLOGY Fall 2008 Partial Examination II Study Guide Dr. Glen S. Mattioli Note that these are NOT questions, but rather are a list of topics that we have covered either in class or are contained within the reading assignments. You should use this list as a guide to help you review what topics are important for the exam. Chapter 8: Time and Geology 1) Development of Geological Reasoning a. Religious perspectives on the age of the Earth b. Hutton & Lyell: The Present is the Key to the Past c. Uniformitarianism relationship to process and rate 2) Principles of Relative Time a. Contacts and formations b. Original Horizontality c. Superposition d. Lateral Continuity e. Cross-cutting Relationships f. Contact Metamorphism and Inclusions 3) Unconformities definitions and differences a. Disconformity b. Angular Unconformity c. Nonconformity 4) Correlation principles and use in relative dating a. Physical Continuity b. Similarity of Lithology and Biofacies c. Methods i. Use of Index Fossils ii. Faunal Succession iii. Fossil Assemblages 5) The Standard Geological Time Scale a. Eras, Periods, and Epochs 6) Numerical or Absolute Ages a. Isotopic Principles and Radioactive Decay Mechanisms b. Half-life and the Decay Constant c. Exponential vs. Linear Decay: Rate Laws d. The Rb/Sr Isochron method e. Reliability of Isotopic Ages 7) Combining Relative and Numerical Ages a. The Age of the Earth i. Modern value of 4.55 By

2 ii. Early Methods and initial estimates b. Revised Geological Time Scale with Numerical Ages Chapter 9: Mass Wasting 1) Classification of Processes a. Rate of Movement b. Type of Material c. Type of Movement 2) Major Divisions of Mass Wasting Movement a. Flow b. Fall c. Slide i. Rotational ii. Translational 3) Factors Controlling Mass Wasting a. Gravity (slope) i. Shear force role in block sliding ii. Shear strength role in debris flows b. Water 4) Commons Types of Mass Wasting Definitions and Characteristics a. Creep b. Debris Flow i. Earthflow ii. Solifluction/Permafrost iii. Mudflow iv. Debris Avalanche c. Rockfalls and Rockslides d. Debris slides and falls 5) Factors That Enhance or Mitigate Mass Wasting a. Undercut slopes b. Vegetation Removal c. Mass Redistribution d. Role of water e. Engineering Methods i. Roadcut design ii. Drainage methods iii. Anchoring methods Chapter 10: Streams and Floods 1) The Hydrologic Cycle a. Solar Energy b. Atmospheric Processes - definitions

3 i. Evaporation ii. Transpiration iii. Precipitation iv. Condensation c. Ground and Surface Water Processes i. Percolation ii. Runoff 2) Channel and Sheet Flow a. Idealized Longitudinal Stream Profile i. Change in gradient along profile ii. Change in channel shape along profiles iii. Headwaters vs. Mouth 3) Drainage Basins Definitions and Examples a. Continental Divides b. Local divides c. Mississippi River System 4) Typical Drainage Patterns Controls and Characteristics a. Dendritic b. Radial c. Rentangular d. Trellis 5) Factors Controlling Stream Erosion and Deposition a. Velocity cross-sections b. Velocity vs. Grain Size Diagram i. Zone of Transportation ii. Zone of Erosion iii. Zone of Deposition c. Gradient d. Channel Shape and Roughness e. Discharge: Definition and Calculation 6) Stream Erosion a. Hydraulic Action Mechanisms i. Plucking ii. Eddy Formation iii. Abrasion b. Hydraulic Action Zones i. Cascades and waterfalls ii. Rapids 7) Stream Transportation a. Sediment Load Definitions and relative carrying capacity i. Bed Load ii. Suspended Load iii. Dissolved Load b. Bed Load Mechanisms i. Traction: Rolling and Sliding ii. Saltation

4 8) Stream Deposition a. Bars: Location and Evolution i. Placer Deposits b. Braided Streams c. Meandering Streams and Point Bars Cross bedding 9) Mature Stream Features and Evolution a. Flood Plains b. Meander Loops and Oxbow Lakes c. Natural Levees and Flood Stage 10) Delta Type and Structure a. Controls i. Waves, Tides, Streams b. Internal Structure i. Topsets-foresets-bottomsets c. Alluvial Fans 11) Floods a. Urbanization Effects b. Recurrence Intervals and Prediction c. Flash Floods i. Causes and Consequences ii. Common Locations d. Controlled Floods 12) The Graded Stream Concept a. Lateral vs. headward erosion 13) Fluvial Geomorphology: relationship to bedrock geology and tectonics a. Stream Terraces b. Incised Meanders c. Superposed Streams Chapter 11: Ground Water 1) World Distribution of Water 2) Porosity and Permeability a. Definitions b. Values for common rock types 3) The Water Table Structure and Definitions a. Vadose Zone b. Capillary Fringe c. Saturated Zone d. Perched water tables e. Change of position relative to rainfall 4) Movement of Ground Water a. Definition of hydraulic head b. Definition of hydraulic gradient c. Darcy s Law and ground water velocity

5 d. Potential and its effect on flow lines 5) Aquifers a. Unconfined b. Confined c. Time for flow from various aquifers 6) Wells a. Good vs. Bad wells b. Drawdown and cones of depression c. Recharge d. Artesian Wells Features and Controls 7) Springs and Streams a. Graining b. Losing c. Dry Stream 8) Ground water contamination a. Sources of pollution b. Plumes c. Aggravation by pumping wells 9) Recharge vs. Withdrawal a. Ground subsidence effects 10) Effects of Ground water action a. Karst features b. Carbonate dissolution and precipitation c. Geysers and Hydrothermal products Chapter 12: Glaciers and Glaciation 1) Glacier Types a. Continental Ice Sheets b. Alpine Glaciers 2) Theory of Glacial Ages a. Global changes in climate b. Global changes in sea level c. Pleistocene Glacial Maximum at 18 Ka 3) Glacier Basics a. Global Distribution b. Volume of water c. Types of glaciers and their characteristics i. Valley glaciers ii. Ice Sheets d. Glacier ice formation: snow, firn, and ice 4) Formation and Growth of Glaciers a. Glacial ice budgets i. Zone of Accumulation ii. Zone of Ablation

6 iii. Equilibrium Line iv. Advancing vs. Retreating systems 5) Movement of Valley Glaciers - Mechanisms a. Meltwater formation and basal sliding b. Rigid zone vs. Zone of plastic flow c. Velocity profile with depth d. Formation and evolution of crevasses 6) Movement of Ice Sheets a. Plastic flow dominates b. Basal sliding may also be important c. Erosion due to overburden of ice 7) Glacial Erosion a. Bedrock grinding: formation of rock flour b. Polished and striated surfaces: direction of flow indicators c. Alpine features i. V- vs. U-shaped valleys ii. Aretes, Horns, spurs, and cirques definitions iii. Hanging valleys and streams iv. Development of rock steps over fractured terrain 8) Glacial Deposition a. Definition and development of till b. Moraines: Location and types i. Medial ii. End iii. Ground iv. Drumlins c. Glacial outwash i. Eskers ii. Kettles iii. Braided streams d. Glacial lakes and varved sediments: relationship to seasons 9) Effects of Past Glaciation a. Glacial Ages i. Glacial vs. Interglacial periods ii. Northern Hemisphere peak glaciation at 18 Ka iii. Antarctic glaciation > 20 Ma b. Direct Effects i. Rock flour -> loess ii. Terminal moraines iii. Great and Finger Lakes iv. Scoured and polished bedrock c. Indirect Effects i. Pluvial Lakes ii. Lowering of Sea Level iii. Fiords iv. Crustal Rebound

7 d. Evidence of Older Glaciation i. Climate fluctuations ii. Ancient Tillites iii. Snowball Earth Hypothesis Chapter 13: Deserts and Wind Action 1) Deserts a. Annual rainfall b. Vegetation type and abundance 2) Global Distribution a. Earth s wind systems i. Latitudinal bands: Trade winds vs. Westerlies in the N hemisphere ii. Hadley Cells related to thermal forcing at the equator iii. Coriolis Force b. Relationship of desert location to global wind systems c. Rainshadows 3) Common Desert Features a. Internal drainage b. Flash Floods c. Arroyos or Dry Washes 4) Desert Features of the SW United States a. Tectonic provinces i. Sierra Nevada ii. Basin and Range iii. Colorado Plateau b. Plateaus, Mesas, Buttes c. Monoclines: Hogbacks and Cuestas d. Basin and Range Topography i. Development of Horsts and Grabens 1. Symmetric, high angle faults 2. Listric normal faults ii. Common landforms 1. Alluvial Fans 2. Playa Lakes 3. Bajadas 4. Pediment 5) Wind Action a. Erosion and Transportation i. Dust storms ii. Ventifacts: features and mechanism of formation iii. Deflation and Blowouts 6) Wind Deposition a. Distribution of loess b. Sand Dune Types: Structure and relationship to winds i. Barchans

8 ii. Transverse iii. Parabolic iv. Longitudinal Chapter 14: Waves, Beaches, and Coasts 1) Wave characteristics a. Wave Height b. Wavelength c. Wave Period d. Orbital particle motion i. Wave Base relationship to wavelength 2) Surf Zone a. Changes in wave characteristics b. Relationship to wave base c. Formation of breakers 3) Near shore Circulation a. Wave refraction b. Longshore current i. Relationship to wind ii. Components of motion c. Rip Currents 4) Beaches a. Structure and relationship to tides b. Seasonal effects on sediment distribution 5) Longshore Sediment Drift a. Drift features i. Baymouth bars ii. Spits iii. Tombolos b. Anthropomorphic intervention i. Jetties, Groins, and Breakwaters ii. Implications for sand movement and distribution c. Sand sources: relative abundance i. Headwall erosion ii. Onshore deposition iii. River deposition and redistribution 6) Coasts and Coastal Features a. Erosional Coasts i. Wave focusing ii. Coastal straightening iii. Landforms 1. Wave cut platforms 2. Stacks 3. Arches

9 b. Depositional Coasts i. Barrier islands ii. Submerged tidal deltas c. Drowned Coasts i. Estuaries ii. Fiords iii. Relationship to glaciation d. Uplifted or Emergent Coasts i. Marine Terraces ii. Relationship to active tectonics e. Coasts shaped by Organisms i. Carbonate platforms and barrier reefs ii. Mangrove swamps f. Coastal evolution i. Long Term Issues 1. Sediment supply 2. Sea Level changes (rising) 3. Increased atmospheric instability due to global warming ii. Short Term Issues 1. Surges related to severe storms and hurricanes

Chapter 5: Glaciers and Deserts

I. Glaciers and Glaciation Chapter 5: Glaciers and Deserts A. A thick mass of ice that forms over land from the compaction and recrystallization of snow and shows evidence of past or present flow B. Types