8.+Geomorphologist%E2%80%99s+Tool+Kit
Page 1: Review Questions
First Step in Elevation Profile Construction
Begin analysis by determining the location for elevational measurements.
Topographic Contour and River Interaction
When a topographic contour intersects a river, the contour lines bend upstream (forming a V-shape).
Primary Physiographic Provinces of Virginia
Coastal Plain
Piedmont
Valley and Ridge
Blue Ridge
Appalachian Plateau
Geologic Evolution of Virginia Over Time
Pre-Cambrian & Cambrian
Major lithologies: Metamorphic rocks, granite, and volcanic rocks formed.
Ordovician/Silurian/Devonian
Major lithologies: Sandstones, shales, and limestones.
Pennsylvanian/Permian & Triassic/Jurassic
Major lithologies: Coal deposits, red beds, and sedimentary rocks.
Cenozoic
Major lithologies: Gravel, sands, clays from depositional environments.
Page 2: A Brief Tectonic History of Virginia
Geologic Timeline and Events
Grenvillian Mountain Building (~1000 Ma)
Lapetan Rifting (~600 Ma): Initiated break-up of supercontinents.
Passive Margin Formation (~500 Ma): Sediments began to accumulate along the shoreline.
Taconic Orogeny (~450 Ma): Major mountain building event.
Acadian Orogeny (~450-300 Ma): Further mountain building as continents converge.
Final Assembly of Pangea (~280 Ma): North America and Africa were extensively joined.
Atlantic Rifting (200 Ma): Creation of new oceanic crust and formation of the Atlantic Ocean.
Modern Passive Margin (present): Current geological setup with ongoing coastal processes.
Major Sediment Types
Carbonate sediment
Clastic sediment
Volcanic-plutonic arc sediments
Page 3: Lab #4 Information
Due Date: Thursday, Feb 13th
Location of Sites:
Ceiles Co Site
Campbell Co Site
Data sources include SIO, NOAA, U.S. Navy, NGA, GEBCO.
Data References
Image Sources: Landsat / Copernicus, Google Earth.
Page 4: Google Earth Pro Overview
Features Available
Search tools for locations, directions, and history.
Organizational folder containing various geospatial and geological data, including:
Marsh site 1 and 2
Stony Creek Dwelling
Niagara Falls
Geological deposits and historical data.
Page 5: Tabb Formation; Lynnhaven Member Description
Lithological Detail
Grades from pebbly and cobbly gray sand upward into clayey and silty fine sand and sandy silt.
Contains medium to coarse cross-bedded sand and clayey silt with abundant plant material.
Surficial deposits found in broad swale, vary in thickness (0-20 feet).
Page 6: Tabb Formation Continued
Geologic Age and Lithology
Age: Quaternary
Composition:
Unconsolidated > Fine-detrital > Silt
Unconsolidated > Coarse-detrital > Sand
Comments: Located in Coastal Plain, significant sediment deposits.
Page 7: Virginia's Geologic Regions
Major Regions:
Appalachian Plateaus
Valley and Ridge
Blue Ridge
Piedmont (Western, Central, Eastern)
Coastal Plain
Mesozoic Basins
Contact Information: Virginia Department of Mines, Minerals and Energy.
Page 8: Tabb Formation Details
Unconsolidated sediment characteristics, low to moderate expansion potential of clays.
Rocks present: Igneous, sedimentary, metamorphic.
Formation depths vary.
Page 9: Lab #4 Hints
Requirements for report include:
One paragraph per site, completed tables, including captions, and charts turned into paragraphs.
Identify rock types at each site, ages, and understand how they were formed.
Page 10: Geomorphologist's Tool Kit, Part 1
Date: Feb 11, 2025
Page 11: Learning Objectives
Techniques covered to include relative and numeric dating methods.
Understand assumptions, uncertainties, and timescales of methods discussed.
Description of C-14 cycle as a chronometer.
Page 12: Toolkit Contents
Methods:
Physical
Chemical (elemental)
Isotopic
Biological
Remote Sensing
Page 13: Tool Considerations
Assess how methods work, acknowledge uncertainties, limitations, and differences between accuracy and precision.
Page 14: Accuracy vs Precision
Accuracy: Closeness to true value.
Precision: Closeness of multiple measurements of the same item.
Page 15: Chronometer - Dating Tool
Techniques categorize as relative (younger or older) and absolute dating (provides numerical ranges).
Page 16: Relative vs Numerical Dating
Relative Dating
General principles include superposition and landform degradation.
Examples: Rock weathering, soil development, rock varnish.
Numerical Dating
Techniques such as Dendrochronology, Radiocarbon dating, K/Ar dating.
Page 17: Dating Methods Overview
Table outlines common dating methods, age ranges, assumptions, and requirements for geomorphologists.
Highlighted methods include Radiocarbon and Cosmogenic nuclides, among others.
Page 18: Relative Dating Techniques
Superposition: Order of layers inversely represents their ages.
Cross Cutting: When one landform cuts another, the former is younger.
Page 19: Repeat of Relative Dating Techniques
Summary of superposition and cross cutting principles.
Page 20: Landform Degradation
Descriptions include features such as colluvial aprons and moraine formations.
Page 21: Fault Example (Figure 3.2)
Illustrates land surface changes over time due to faulting and erosion processes.
Page 22: Photograph 3.5
Displaying geomorphological features (STOP).
Page 23: Weathering Rind
Measurement of thickness provides estimations for time since last fracturing.
Page 24: Rock Varnish
Contains iron and manganese; forms from biological activity on surfaces over time.
Page 25: Lichenometry
A calibrated relative dating method examining growth rates of lichens linked to surface age.
Page 26: Numerical Dating Methods
Discusses assumptions and limitations attached to various dating techniques.
Page 27: Dendrochronology
Annual tree rings indicate past climate conditions; width correlation with stress and growth periods.
Page 28: Research Sources
Suggested materials for deeper understanding of dendrochronology.
Page 29: Historical Megadroughts Timeline
Graphical representation of significant climatic events impacting growth conditions.
Page 30: Tree Ring Analysis Graphical Representation
Highlights environmental conditions affecting growth rates over time.
Page 31: Photomicrograph of Tree Rings
Example of tree ring analysis showing impacts of specific climatic events.
Page 32: Flow Reconstruction
Analysis of water flow over time utilizing tree cores, illustrating significant hydrological patterns.
Page 33: Radiocarbon Dating Overview
Key points on Carbon-14 production and decay mechanics.
Page 34: Nuclear Interaction for Radiocarbon Production
Description of cosmic-ray neutron interactions creating Carbon-14.
Page 35: Radiocarbon Production Process (Figure 3.5)
Details the process of Carbon-14 formation and its ecological impact through food chains.
Page 36: Radioactive Decay of Radiocarbon
Graphical representation of decay over time relevant for dating.
Page 37: Radiocarbon Dating Utility
Advantages of using radiocarbon techniques for organic material dating.
Page 38: Radiocarbon Decay Measurement Mechanism
Equipment and procedures necessary for accurate decay readings.
Page 39: Specific Activity Calibration (Figure DD3.1)
Details on calibration curves involving samples of known ages to ensure accuracy.
Page 40: Radiocarbon Dating Equation
Formula presented for calculating radiocarbon age, integrating percent modern carbon.
Page 41: Calculating Radiocarbon Age Example
Exercise in determining radiocarbon age based on provided parameters.
Page 42: Calibration Program for Radiocarbon Age
Instructions for entering and adjusting sample data in calibration software.
Page 43: Age Calibration Curve Overview
Illustrates the relationship between radiocarbon dates and calibrated ages.
Page 44: Radiocarbon Calibration Necessity
Important factors affecting radiocarbon dating accuracy, such as atmospheric changes.
Page 45: Atmospheric Radiocarbon Level Changes
Graph showing how changes can impact radiocarbon dating results.
Page 46: Summary of Dating Methods (Table 3.1)
More detailed table covering methods frequently used for dating by geomorphologists.