U.S. Geological Survey 2016 geodatabase Online U.S. Geological Survey Recommended Citation: Carter, M.W., Crider, E.A., Southworth, C.S., and Aleinikoff, J.N., 2016, Detailed geologic mapping geodatabase for the Blue Ridge Parkway in Virginia with station point photographs: U.S. Geological Survey data release, http://dx.doi.org/10.5066/F7DN434F. http://dx.doi.org/10.5066/F7DN434F The US Geological Survey, in cooperation with the National Park Service, mapped 35 7.5-minute quadrangles, within a 2-mile-wide+ corridor centered on the Parkway, from BLRI (Blue Ridge Parkway) Mile Post (MP) 0 near Afton, Virginia southward to MP 218 at Cumberland Knob, approximately 1.3 km south of the Virginia – North Carolina State Line. Detailed bedrock geologic mapping for this project was conducted at 1:24,000-scale by systematically traversing roads, trails, creeks, and ridges within and adjacent to the 2-mile-wide+ corridor along the 216.9-mile length of the BLRI in Virginia. Geologic data at more than 23,000 station points were collected during this project (September 2009 – February 2014), with approximately 19,500 included in the accompanying database. Station point geologic data collected included lithology, structural measurements (bedding, foliations, folds, lineations, etc), mineral resource information, and other important geologic observations. Station points at the start of this project (September 2009) were located in the field using topographic reckoning; after May 2012 stations were located using Topo Maps (latest version 1.12.1) for Apple IPad 2, model MC744LL/A. Since the start of the project, station point geologic data and locational metadata were recorded both in analog (field notebook and topographic field sheets) and digitally in ESRI ArcGIS (latest version ArcMAP 10.1). Station point geologic data were used to identify major map units, construct contact lines between map units, identify the nature of those contacts (igneous, stratigraphic or structural), determine contact convention control (exact – located in field to within 15 meters; approximate – located to within 60 meters; inferred – located greater than 60 meters), trace structural elements (faults, fold axes, etc) across the project area, and determine fault orientation and kinematics. Geologic line work was initially drafted in the field during the course of systematic detailed mapping; line editing occurred during office compilation in Adobe Illustrator (latest version CS 4). Final editing occurred during conversion and compilation of Illustrator line work into the ArcGIS database, where it was merged with station point geologic data. Station point geologic data, contacts and faults from previous work in the BLRI corridor were evaluated for compilation and synthesis in the BLRI mapping project. Station point geologic data compiled from previous work are referenced and marked with a “C” in the database. Compiled line work is also clearly tagged and referenced. The BLRI cuts at an oblique angle nearly the entire width of the Blue Ridge Geologic Province in Virginia. Thus, the geology varies significantly along it’s along its 216-mile traverse. North of Roanoke (BLRI MP 115), the Blue Ridge is defined as an orogen-scale, northwest-vergent, northeast-plunging reclined anticlinorium, and from its start at MP 0 near Afton, Virginia, southward to Roanoke, the BLRI traverses the western limb of this structure. Here, rocks range in age from Mesoproterozoic to Cambrian: Mesoproterozoic orthogneisses and metamorphosed granitoid rocks of the Shenandoah massif comprise “basement” to Neoproterozoic to Cambrian mildy- to non-metamorphosed to sedimentary “cover” rocks; the BLRI crisscrosses in many places the contact between cover and basement. Mesoproterozoic basement rocks in the Shenandoah massif represent the original crust of the Laurentian (ancestral North American) continent; sedimentary cover rocks were deposited directly on this crust during extension and breakup of the Rodinian supercontinent in the Neoproterozoic to earliest Cambrian. Very locally, diabase dikes of earliest Jurassic age intrude older basement and cover sequences. These dikes were emplaced in the Blue Ridge during continental extension (rifting) and the opening of the Atlantic Ocean in the Mesozoic Era. From MP 103.3 to MP 110.3 near Roanoke, the BLRI crosses into and out of a part of the Valley and Ridge Geologic Province. Unmetamorphosed sedimentary rocks of Cambrian to Ordovician age – mostly shale, siltstone and carbonate – occur here. These rocks were deposited in a terrestrial to shallow marine environment on the Laurentian continental margin, after extensional breakup of Rodinian supercontinent in the Neoproterozoic and earliest Cambrian, but before mid- to late-Paleozoic orogenesis. South of Roanoke, the Blue Ridge Geologic Province quickly transitions from an anticlinorium to a stack of imbricated thrust sheets. After crossing the southern end of the Shenandoah Mesoproterozoic basement massif (MP 124.1 to MP 144.4), the BLRI enters the eastern Blue Ridge province, a fault-bounded geologic terrane comprised of high-metamorphic-grade sedimentary and volcanic rocks deposited east of the Laurentian continental margin from the Neoproterozoic to early Paleozoic. These rocks were significantly metamorphosed, deformed, and transported westward onto the Laurentian margin along major orogenic faults during Paleozoic orogenesis. Sixty bedrock map units underlie the BLRI in Virginia. These units consist of one or more distinguishing lithologies (rock types), and are grouped into formal and informal hierarchal frameworks based on age, stratigraphy (formations-groups), and tectonogenesis. Many of these units exhibit characteristics and field relationships that are critical to our understanding of Appalachian orogenesis. Most of these units are named based on the dominant occurring lithology; other units follow formal nomenclature, some of which was developed and has been used for more than 100 years. Oldest rocks occurring along the BLRI corridor are Mesoproterozoic orthopyroxene-bearing basement rocks of the Shenandoah massif, in the core of the Blue Ridge anticlinorium. Preliminary SHRIMP U-Pb zircon geochronology (J. N. Aleinikoff, this study) shows that these rocks can be grouped based on crystallization ages: Group I (~1.2 to 1.14 Ga) are strongly foliated orthogneisses and Group II (~1.06 to 1.0 Ga) are less deformed metagranitoids. Group I orthogneisses, which occur discontinuously from near Irish Gap (MP 37) to Cahas Overlook (MP 139), comprise 10 map units: leucogranitic gneiss (Yllg); megacrystic quartz-monzonitic gneiss (Yqg); granitic gneiss (Yg); lineated granitoid gneiss (Ylgg); garnetiferous leucogneiss (Yglg); Sandy Creek gneiss (Ysg); porphyroblastic garnet-biotite leucogranitic gneiss (Ygtg); dioritic gneiss (Ydg); Pilot gneiss (Ypg); and megacrystic granodioritic gneiss (Ygg). Group II metagranitoids, which are first encountered along the BLRI at Reeds Gap (MP 14) and occur discontinuously to Roanoke River Overlook (MP 115), comprise 8 map units: megacrystic meta-quartz monzonitoid (Yqm); massive metagranitoid (Ymgm); megacrystic metagranitoid (Ypgm); mesocratic porphyritic metagranitoid (Ygpm); metagranodioritoid (Ygdm); Vesuvius megaporphyritic metagranitoid (Yvm); quartz-feldspar leucogranitoid (Yqfm); and Peaks of Otter metagranitoid (Ypom). An additional relatively undeformed metagranitoid with a preliminary SHRIMP U-Pb zircon age of ~1.12 Ga is assigned to the Bottom Creek Suite (Ybcm), and well layered migmatitic gneiss (Ymg) near Irish Gap (MP 37) has a a preliminary SHRIMP U-Pb zircon age of ~1.05 Ga. Other rocks of Mesoproterozoic age include orthogneisses in the Fries thrust sheet between MP 139 and MP 144.5 that range in age from ~1.19 to ~1.07 Ga: biotite-muscovite leucogneiss (Ymlg); biotite granitic augen gneiss (Ybgg); blue-quartz gneiss (Ybqg); and biotite leucogneiss (Yblg). Latest Mesoproterozoic rocks include paragneiss and pegmatite (Yprg) near Porters Mountain Overlook (MP 90), and a suite of igneous intrusive nelsonites and jotunites (Yjn). Two units, foliated metagreenstone (Zdm) and foliated metagranitoid (Zgm), locally intrude older Mesoproterozoic rocks in the core of the Blue Ridge anticlinorium. Metagreenstone is fine-grained and mafic in composition, and occur as narrow dikes and sills; metagranitoid is medium-grained and generally felsic in composition, and intrude basement rocks as small plutons, stocks, and a few narrow dikes. On the west limb of the Blue Ridge anticlinorium, metamorphosed sedimentary and volcanic rocks of Neoproterozoic to Cambrian age crop out discontinuously along the BLRI from near Afton (MP 0) to MP 103.3, in the vicinity Roanoke Mountain (MP 120 to MP 124), to near Adney Gap (MP 136). These rocks are assigned to a formal stratigraphic sequence: Swift Run Formation; Catoctin Formation; Chilhowee Group. Metasedimentary and meta-igneous rocks of lower Paleozoic (?) to Neoproterozoic age are assigned to the Alligator Back Formation, Lynchburg Group, and Ashe Formation. These units crop out southeast of the Red Valley fault from MP 144.5 southwestward to the North Carolina–Virginia State Line at Mile Post 216.9. Rocks assigned to the Alligator Back crop out in the Blue Ridge Parkway corridor from Mile Post 174.5 southward to the North Carolina–Virginia State Line: compositional-layered biotite-muscovite gneiss (abg); garnet-biotite-muscovite-quartz schist (abs); quartzite and quartz-rich metasandstone (abq); and marble (abm). The following lithologic map units along the BLRI corridor are correlated with Lynchburg Group formations: graphitic schist (lgs), muscovite-biotite metagraywacke (lmg), and graphite-muscovite-quartz metasandstone (lms). These rocks crop out between the Red Valley fault (Mile Post 144.5) and the Rock Castle Creek fault (Mile Post 174.5). Coarse-grained- to conglomeratic metagraywacke (acm), underlying Lynchburg Group rocks west of the Rock Castle Creek fault in the vicinity of Rakes Millpond (MP 162.3) and Rocky Knob Visitors Center (MP 169), are considered to be the lower metamorphic grade-equivalent of the higher metamorphic-grade Ashe Formation at its type section in northwestern North Carolina. Five meta-igneous lithologic map units occur as mappable bodies interlayered or intrusive into metasedimentary rocks of the Alligator Back Formation and Lynchburg Group. Altered ultramafic and ultrabasic rocks (um) occur mostly within the Lynchburg Group, but few thin bodies also occur within laminated amphibolite gneiss (aml) locally (laminated amphibolite gneiss is associated with rocks of the Alligator Back Formation). Amphibolites of the Lynchburg Group include biotite-bearing amphibolite (amb), clinozoisite-bearing amphibolite (amc) and quartz-layered amphibolite (amq). Map units that occur beneath the Blue Ridge fault are assigned to the Valley and Ridge Province. In the BLRI corridor, these rocks are first exposed near Bearwallow Gap (MP 91) and continue southward beyond Roanoke near MP 125. Oldest formations are Shady Dolomite (Cs) and Waynesboro Formation (Cw), which regionally can be mapped in stratigraphic continuity with cover and basement rocks of the Blue Ridge anticlinorium. Conversely, nowhere in the Appalachians can rocks of the Elbrook Formation (Ce) or Conococheague Formation (Cco) be mapped in direct stratigraphic continuity with Mesoproterozoic basement rocks in the core of the Blue Ridge anticlinorium; however, they do stratigraphically overlie older Waynesboro Formation and Shady Dolomite within imbricates of the Blue Ridge fault system. Ordovician Martinsburg Formation (Omb) occurs beneath the Pulaski fault north of Roanoke River, about 0.85 km northwest of MP 108. Paleozoic mylonite (Pzmy) is a tectonic rock unit that that occurs in high-strain fault zones in the core of the Blue Ridge anticlinorium from near Afton (MP 0) to Adney Gap (MP 136). Jurassic diabase (Jd) occurs in narrow dikes that intrude older map units, just south of Roanoke River near MP 118 and MP 125, north of James River near MP 56, and in the vicinity of Afton near MP 3 and north of MP 0. The geologic map database for the Blue Ridge Parkway can be utilized to address numerous county and state, land-use, and environmental issues. Possible applications of this database include the study of landslide hazards, groundwater resource issues, land-use planning for growing communities, and further studies related to earthquake hazards. These data can also be used to study the close association between bedrock geology, overlying soils and surface ecology. All of these applications require accurate, concise, and user-friendly geologic map data to produce viable derivative products and to enable sound land-use decisions. This database is NCGMP09 compliant with some modifications. These modifications include additional fields in points feature classes, including MapDescription (used by the Author for the actual map description on a printed map); RockType (used by the author to describe the rock in the field). The DescriptionofMapUnits table contains modifications to the Description field, many descriptions for rock units exceeded the standard column width and therefore the width was modified. In addition, many of those descriptions contained multiple DataSourceIDs so the notes field includes the additional data sources in the DataSource table. The RepurposedSymbols table was not completed but more information about repurposed symbols can obtained on request. A list of the U.S. Geological Survey quadrangles used in preparation of this database is listed below with publication dates listed in parenthesis: Arnold Valley, Virginia (1999) Bent Mountain, Virginia (1996) Big Islands, Virginia (1999) Big Levels, Virginia (1999) Buena Vista, Virginia (1999) Callaway, Virginia (1963) Cana, Virginia - North Carolina (1968) Check, Virginia (1963) Cornwall, Virginia (1967) Cumberland Knob, North Carolina - Virginia (1965) Elliston, Virginia (1963) Endicott, virginia (1967) Fancy Gap, Virginia (1968) Floyd, Virginia (1968) Garden city, Virginia (1999) Hardy, Virginia (1963) Lambsburg, Virginia - North Carolina (1965) Laurel Fork, Virginia (1968) Massies Mill, Virginia (1999) Meadows of Dan, Virginia (1985) Montebello, Virginia (1999) Montvale, Virginia (1967) Peaks of Otter, Virginia (1967) Roanoke, Virginia (1963) Sedalia, Virginia (1965) Sherando, Virginia (unknown) Snowden, Virginia (1999) Stewartsville, Virginia (1963) Vesuvius, Virginia (1965) Villamont, Virginia (1999) Waynesboro East, Virginia (1997) Waynesboro West, Virginia (1973) Willis, Virginia (1968) Woodlawn, Virginia (1965) Woolwine, Virginia (1968) 2009 2014 ground condition Complete None planned -80.944912058 -78.83821867 38.067616116 36.523979729 None Alligator Back Formation Ashe Formation Lynchburg Group Antietam Formation Ervin Formation Hampton Formation Harpers Formation Conococheague Formation Chilhowee Group Weverton Formation Elbrook Formation Shady Dolomite Wayneboro Formation Unicoi Formation Martinsburg Formation Bottom Creek Metagranitoid Suite Mesoproterozoic gneisses of the Fries Thrust Sheet Pilot Gneiss Sandy Creek Gneiss Crossnore Plutonic Suite Swift Run Formation Peaks of Otter Metagranitoid Geology Bedrock Thrust Fault Normal Fault Reverse Fault Folds Gneiss Granite Metagranitoid Carbonate Diabase Structure Metabasalt USGS Metadata Identifier USGS:56ce06f6e4b0b1892d9f0e89 None Blue Ridge Parkway Virginia North Carolina Waynesboro Humpback Rocks Visitor Center Greenstone Trail Ravens Roost Humpback Mountain Sherando Lake Bald Mountain Twenty Minute Cliff Crabtree Faults Tye River Gap Tye River Wigwarm Falls Yankee Horse Ridge Irish Gap George Washington National Forest Whites Gap Overlook Indian Gap Buena Vista Bluff Mountain Otter Creek James River Big Island James River Visitor Center and Canal Petites Gap Terrapin Mountain Onion Mountain Overlook Fallingwater Cascades Peaks of Otter Visitor Center Sharp Top Bearwallow Gap Purgatory Overlook Powell Gap Jefferson National Forest Blackhorse Gap Great Valley Overlook N&W Railroad Overlook Roanoke River Gorge Roanoke River Roanoke Mountain Virginia Explore Park and Visitor Center Staunton River Roanoke Valley Overlook Adney Gap Poor Mountain Devils Backbone Overlook Rakes Millpond Sugarloaf Mountain The Saddle Rocky Knob Rocky Knob Visitor Center Mabry Hill Meadows of Dan Groundhog Mountain Puckett Cabin Volunteer Gap Orchard Gap Fancy Gap Pipers Gap Blue Ridge Music Center Visitor Center Fox Hunters Paradise Cumberland Knob Stone Mountain State Park Doughton Park Air Bellows Gap Bluff Mountain Peach Bottom Mountain Laurel Springs Northwest Trading Post Jumpinoff Rock Glendale Springs Mount Jefferson State Park The Lump Benge Gap E.B. Jeffress Park Deep Gap Daniel Boone's Trace Blowing Rock Moses H. Cone Memorial Park and Visitor Center Price Lake Watauga River Julian Price Memorial Park Grandfather Mountain State Park Grandfather Mountain Beacon Heights Pisgah National Forest Flat Rock Linville Lineville River Pineola Linville Falls Visitor Center Crossnore Linville Falls Hawksbill Mountain Table Rock Mountain Chestoa View Bear Den McKinney Gap Gillespie Gap Overmountain Victory Nation Historic Trail Woodlaw Museum of North Carolina Minerals Visitor Center Little Switzerland Crabtree Falls Buck Creek Gap Mount Mitchell Mount Mitchell State Park Green Knob Bear Mountain Gap Graggy Dome Beetree Gap Swannanoa River Craggy Gardens Visitor Center Bull Gap Z.B. Vance Birthplace Craven Gap Ashville Oteen Blue Ridge Park Visitor Center and Park Headquarters Skyland Biltmore Estate North Carolina Arboretum Lake Powhaten Hominy Creek Mount Pisgah Elk Pasture Gap Wagon Road Gap Cold Mountain Tunnel Gap Looking Glass Rock Overlook Graveyard Fields Devils Courthouse Beech Gap Wayneville Richland Balsam Nantahala National Forest Balsam Gap Waterrock Knob Visitor Center Cherokee Indian Reservation Wrights Creek Southern End Oconalufte Visitor Center Big Witch Gap Cherokee Ervin None Early Paleozoic Paleozoic Neoproterozoic Cambrian Jurassic Mesoproterozoic None None. Acknowledgment of the U.S. Geological Survey would be appreciated in products derived from these data. Although software enables the user to display images at various scales, map data in this report should not be used at scales greater than 1:24,000 U.S. Geological Survey, Eastern Geology and Paleoclimate Science Center Mark W Carter Research Geologist mailing address

Mail Stop 926A, 12201 Sunrise Valley Dr

Reston VA 20192 United States of America 703-648-6910 703-648-6953 mcarter@usgs.gov Field Work and Compilation: Mark W. Carter (2006-2015) GIS and Cartography: E. Allen Crider Jr (2011-2015) Environment as of Metadata Creation: Microsoft Windows 7 Version 6.1 (Build 7601) Service Pack 1; Esri ArcGIS 10.1 (Build 3035) Service Pack N/A (Build N/A) Geologic contacts and information were garnered from 1:24,000-scale mapping of geologic material based on observation from fieldwork, previously published geologic maps, and unpublished geologic data in the region. The geologic information might change if additional outcrops are discovered or exposed as the natural land changes, or as the result of development, or advances in scientific research are made. The features in the database are not based on legal parcels or definitions. These data are believed to be logically consistent, though no tests were performed. Geometry is topologically clean. Data set is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details. The data were created on a USGS 7.5-minute topographic map at 1:24,000 scale. Therefore, the horizontal accuracy is assumed to be within National Map Accuracy Standards, with a horizontal accuracy of 45.6 feet at the 95% confidence level. The data were delineated on a USGS 7.5-minute topographic map at 1:24,000 scale. Therefore, the vertical accuracy is assumed to be within National Map Accuracy Standards, with a vertical accuracy of 11.9 feet at the 95% confidence level. Process description is provided individually for each dataset with this geodatabase. Unknown This dataset collectively consists of 7 GIS data files and a saved topology layer. The data consist of point, line, and polygonal feature classes in an ESRI geodatabase. For more detailed information, including explicit feature counts, etc. please see the metadata records for the individual files. Universal Transverse Mercator 17 0.9996 -81.0 0.0 500000.0 0.0 coordinate pair 0.6096 0.6096 Meter D_North_American_1927 Clarke_1866 6378206.4 294.9786982 Entity and attribute information is provided individually for each dataset within this geodatabase. The entity and attribute information was generated by the individual and/or agency identified as the originator of the data set. Please review the rest of the metadata record for additional details and information. U.S. Geological Survey - ScienceBase mailing address

Denver Federal Center, Building 810, Mail Stop 302

Denver CO 80225 United States of America 1-888-275-8747 Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this information product, for the most part, is in the public domain, it also contains copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner whenever applicable. The data have been approved for release and publication by the U.S. Geological Survey (USGS). Although the data have been subjected to rigorous review and are substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, the data are released on the condition that neither the USGS nor the U.S. Government may be held liable for any damages resulting from authorized or unauthorized use. Although the data have been processed successfully on a computer system at the U.S. Geological Survey, no warranty expressed or implied is made regarding the display or utility of the data on any other system, or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. The U.S. Geological Survey shall not be held liable for improper or incorrect use of the data described and/or contained herein. Users of the data are advised to read all metadata and associated documentation thoroughly to understand appropriate use and data limitations. Geodatabase (.gdb) http://dx.doi.org/10.5066/F7DN434F None. No fees are applicable for obtaining the data set. 20200819 Ernest A Crider U.S. Geological Survey, Eastern Geology and Paleoclimate Science Center Geologist mailing address

Mail Stop 926A, 12201 Sunrise Valley Dr

Reston VA 20192 United States of America 703-648-6906 703-648-6953 ecrider@usgs.gov FGDC Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998 local time