Skip to main content
Geosciences LibreTexts

5.5: Geologic Map

  • Page ID
  • \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)


    This is the map of the area (without annotations):


    Here is an annotated map of the area, showing approximate sample locations and towns, as well as the Fries Fault and major structural units:


    Rock Units

    Formation Age Sample # Rock Type Protolith
    Ashe Formation Protolith Age: 600 Ma (Late Proterozoic). Age of metamorphism: 450-430 Ma. A1 B2, A3 schist Staurolite Schist (Pelite) Fine-grained mudstone
        A1 amph, A3 Amph Amphibolite Basalt or Gabbro
        UM1 Soapstone / serpentinite Ultramafic (peridotite)
    Fries Fault Zone Fault Age To Be Determined A4 Mylonite 1 Mylonite Cranberry Gneiss
        A4 Mylonite 2 Mylonite Ultramafic or mafic protolith
    Cranberry Gneiss Protolith Age: ~1.1 Ga (billion years) Age of metamorphism: gneissic fabric – 900 Ma? faulting age is unknown. Cranberry Orthogneiss Granite
        S5 Cranberry Paragneiss Sedimentary
    Striped Rock Granite Crystallization age ~690 Ma. Perhaps associated with Mt Rogers volcanics (~750 Ma)? S6 Striped Rock Granite Not applicable
    Unicoi Formation Early Cambrian (like the Chilhowee Group near JMU) Unicoi 1 Shale / mudstone Not applicable
        Unicoi 2 Greenstone Basalt
        Unicoi 3 Conglomerate Not applicable

    Field Bulletin

    The map and field descriptions of this area (by Stose and Stose) are available here:

    And from this page (it is free to download, even though it is the DMME “store”):

    Like most map bulletins, the text is first, and the maps are at the very end of the .pdf document.

    This page titled 5.5: Geologic Map is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Elizabeth Johnson and Juhong Christie Liu (Virtual Library of Virginia) via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.