VIRGINIA GEOLOGICAL SURVEY ARTHUR BEVAN, State Geologist
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COMMONWEALTH OF VIRGINIA STATE COMMISSION ON CONSER,VATION AND DEVELOPMENT VIRGINIA GEOLOGICAL SURVEY ARTHUR BEVAN, State Geologist Bulletin 5O Ground-water Resources of Northern Virginia BY R. C. CADY Pnrpanno rN CoopenarroN wrrrr rnn lJrvrrno Srnres GBor-ocrcnr, Sunvey T]NIVERSITY, VIRGINIA 1938 RICHMOND: Drvrsrox or Puncnast aNo PnrntrNc DIVISION OF MINERAL RESOURCE$ P. O. Box 3667, UniversitY Station Charlottesville' Virginis Vrncrxr,t Geolocrcat Surr,riy BunnrrN 50 Pr-arn I b0 o' !s]. (nu!@ id uo 6aa '6i o. F8 tn 6G ,eE I ". a- bi- Fo -4, > r;g o<B >6o G (4'; 4". -d .-O ! Vtuc;trir,r Gtolocrcrr Suur l:r llulloux 50 Prern I d bro tr-Y ia Av aaa '&ai6 r>A {l =LJ 6J -N -iE It9v 6,f- -a> 6E OO ;E "/ 6 ! STATE COMMISSION ON CO\ISERVATION AND DEVELOPMENT Wrr,sun C. Har,r, Chairman, Richmond BneueN VaxoBvnxrax, V ic e-C hairwan, Norfolk Mansuar,r, B. BoorBn. Halifax C. S. CanrBn, Bristol D. D. Hur,r, Jn., Roanoke Rrcrreno A. Grr-r,reu, Erecutiae Secretary and, Treasurer, Richmond 111 LETTER OF' TRANSMITTAL CoulroNwBALTrr oF VrncrNre VrncrNre GBorocrcer Sunvnv IJNrvensrrv or VrncrNre Cuanr-orrBsvrr,r,tr, Va., January 25, 1938. To the State Comtnission otc Consetwatiorc anrl Develobntent: GeNrrurrBN: I have the honor to transmit and recommend for publication as Bulletin 50 of the Virginia Geological Survelz series of reports the manuscript and illustrations of the Ground,-zaater Resowrce.s of Nortkern Virginia, by Mr. R. C. Cady of the United States Geological Survey. This report is the second complete one of a series based on detailed field investigations of the ground-water resources of Virginia made in cooperation with the United States Geological Survey. The previous re- port is Virginia Geological Survey Bulletin 45, Grownd,-zaater Resources of the Shenand,oak Valley, Virginia, published in 1936" Because of the lack of and urgent need for fundamental data about the occurrence of ground water in the diverse rocks in Virginia, a Prelkninwy Report on Grownd,-water Resowrces of Northern Virginia was published in 1933 as Bulletin 41 of the State Geological Survey. The occurrence and quality of the ground water in Arlington, Ciarke, Fairfax, Frederick, Loudoun, and Prince William counties are described in detail in this report, which gives also information concern- ing some wells in adjacent parts of Fauquier, Shenandoah, and Warren counties. In addition, the occurrence of ground water in relation to types of rocks and rock structure and the water-bearing properties of the rocks underlying northern Virginia are discussed. The report in- cludes a brief summary of the geography, climate, drainage, geomor- phology and geo ogy of that part of the State. As the amount and distribution of ground water depend upon local conditions and as there is a great demand for reliable, up-to-date in- formation about these conditions by industries, municipalities and prop- erty owners, this report should be of value to everyone interested in northern Virginia. Respectfully tuo-ttt"X.uruun BoveN. State Giotogist. Approved for publication: State Commission on Conservation and Development, Richmond. Virginia, January 31, 1938. R. A. Grr,r,re.w, Erecutizte Secretary and, Treucurer. CONTENTS Pacn Abstract I Introduction 4 Geography 6 Population - 6 Agriculture 8 Climate -- --. g Temperature 9 Precipitation 9 Drainage -__. lz Geomorphology - - 13 Valley and Ridge province -- - --. 13 Blue Ridge province 14 Piedmontprovince-.-_ - 14 Coastal Plain province --- 15 Outline of rock {ormati<-rns Geologic history and structur€ _ _, Zs Occurrence oI ground water in relation to rock structure_.____ _____-___ _ , 27 Occurrence of ground water in relation to the principal types of rocks_- 31 Igneous rocks _-_ 3l Metamorphic rocks ____________"_ 31 Sedimentary rocks - 32 Observation wells ___ 33 Water-bearing properties of the rock formations 39 Pre-Cambrian white marble __ _ __ 39 Catoctin greenstone -- , 39 ffi:'.i1fT:#1"'__ __ . ._ _ _____ _- ii _ Granite of the eastern belt __-_- ___ ___ ____ 43 I-oudoun formation, Weverton sandstone, Harpers shale, and Antietam sandstone 44 Tomstown dolomite 46 Waynesboro formation -______ 4Z Elbrook and Conococheague limestones ___-_ 47 Beekmantown limestone, Stones River group, Athens (?) limestone, and Chambersburg limestone 49 Quantico slate, Martinsburg shale, and Oswego sandstone_,-,_ 51 Juniata formation, Tuscarora sandstone, Clinton formation and Cayuga gfoup -_____ _,____,_-,____ 52 Helderberg limestone 53 Oriskany sandstone 54 Romney shale, Jennings formation, and Catskill formation 54 V111 LONTENTS Pacr Newark formation and associated diabase - ,- 55 Trap or diabase -- 5E Potomac group 59 Pliocene(?), Pleistocene, and Recent deposits-,,--, 60 Summary -,- - 6l Ground-water conditions, by counties -. - ,, -, --- 62 Frederick County 62 Ceography 62 Drainagc ----- - 62 Topography - ----.- 63 Geology ------. 63 Ground-water conditions 65 Martinsburg shale belt 65 Belt of Cambrian and Ordovician limestone 66 Area west oI Little North Mountain ----- ---- 68 Muncipalsupplies- - 69 Well records -- 70 Analyses of water -------- 80 Adjacent areas in Shenandoah and Warren counties---- 82 ClarkcCounty--- --- 84 Geography 81 Drainage . - 84 Topography 84 Geology 85 Ground-water conditions 85 Blue Ridge area -------- 85 Valley and Ridge area 86 Municipal supplies 86 Weil records 88 Analyses of water 92 Loudoun County ------ * -,--- -- 93 Geography 93 Drainase 93 Topography 94 Geology 94 Ground-lvater conditions 95 Catoctin-Blue Ridge area 95 Area of Triassic rocks ,---- -- 97 Municipal supplies 98 Wellrecords-, 100 Analyses of water --- , ------ 116 Adjacent area in Fauquier County ----- -,- 118 Prince William County 123 Geography 123 Drainage ,,---- -,123 Topography ,-'-- 123 CoN:rBr.rrs 1X Pece Geology 124 Ground-water conditions 125 Area of Triassic rocks - LZJ Area of crystalline rocks _-___ t?6 Coastal Plain area 127 Municipal supplies -__ ____ lZ7 Malassas _-_ _ 127 euantico vg Well records _ - __ f30 Analyses o{ water Vg Fairfax County - __ 150 Geography _ ___l5o ' Drainage and topography _ ____ lsC Geology _ _ __- __-_ 151 Ground-water conditions fiz Area Triassic of rocks __ ___ _ lS2 Area of crystalline rocks -__-__- _- __-___ i53 Coastal plain area __- __ 155 Municipal supplies _,__- __ 156 Fairfax _- _ ___ __ 156 Herndon 156 Fort Hunt 156 Fort Humphreys --- -- --- - -_- 156 Water supply of Falls Church _,.- _- Well records 156 - ___- 160 Analyses of water ___ _ Arlington 166 County _ __ __, lg\ Geographl. 187 Drainage and topbgraphy -__ _- _-,_____ - lg7 Geology _ _ 18g Ground-water conditions lgg Area of crystalline - rocks -__ _, __ __ lgg Coastal plain area _- __ lgg Municipal - supplies .____ lg9 Wellrecords __190 Analyses of lvater __- _ _-- *, i96 Index - -----_- 197 ILLUSTRATIONS Prerp Pecr l. Erosion surfaces in the Shenandoah Valley near Strasburg.- -_ Frontispiece 2. Geologic map of northern Virginia 12 3. A, Schistose granite in road cut south of Manassas; B, Tuscarora quartzite at north end of Massanutten Mountain __ - 32 4. A, Valley-floor peneplain and Sleepy Creek Mountain; B, Large spring issuing from Beekmantown dolomite near Vaucluse____- _,_ , 32 5. Hydrographs of observation wells in Arlington and Fairfax counties_ 34 6. A, Newark formation in railroad cut along Manassas-Warrenton road, Prince William County; B, Trap in road cut at intersection of Manas- sas-Warrenton road with Lee Highway, Fauquier County-._-_-,_,,_ 48 7. A, Granite in quarry 1 mile west of Falls Church; B, Residual soil de- veloped on Wissahickon schist _ - 48 Frcunn paco 1. Record of rainfall at Washington, D.C., for the period 1870-1937_____ ll 2. Block diagram of an eroded pitching anticline____--_ -, ___ 2Z 3. Block diagram of an eroded pitching syncline ______________ Zg 4. Structure section across Frederick and Clarke counties- ____ _________ Zg 5. Fluctuations of the water level in the Ross well, caused by changes in the atmospheric pressure 37 TABLES Pace l. Area and population of counties and independent cities in northern Vir- ginia, in 1930 _ - 6 2. Population of the larger communities of northern Virginia, by coun- ties, in 1930 --- - 7 3. Number of industrial establishments and value of products, by coun- ties. in 1929 8 4. Percentage of area in northern Virginia in farms, by counties, in 1930__ 8 5. Mean monthly and annual air temperature at U. S. Weather Bureau stations in northern Virginia and the District of Columbia__ 10 6. Mean monthly and annual precipitation, in inches, at U. S. Weather Bureau stations in northern Virginia and the District of Columbia 10 7. Geologic formations in northern Vireinia,-- , 16 TaeLns x1 Pecp B. Physical properties of water-bearing materials from the Bell and Swart wells, Fairfax County 36 9. Average yield of wells ending in Catoctin greenstone in relation to depth oi wells 39 10. Average yield of wells in the Wissahickon schist for each 100 feet of depth - _ 4l 11. Average yield of wells ending in the \{arshall granite for each 100 feet of depth 42 12. Average yield of wells ending in the granite of the eastern beit for each 100 feet of depth *----- ,_______-_____ 43 13. Average yield of wel1s ending in the Lower Cambrian rocks for each 100 leet of depth 45 14. Average yield of we1ls ending in the Elbrook and Conococheague lime- stones for each 100 feet of depth_ ________ 48 15. Average yield of wells ending in the Beekmantown, Stones River, Fred- erick, Athens (?), and Chambersburg limestones for each 100 feet o{ depth 50 16. Average yield of wells ending in the Martinsburg shale for each 100 feet of depth ______________ 5l 17. Average yield of wel1s ending in the Quantico slate for each 100 feet of depth __ _______-,_, 52 18. Yield of wells ending in the Helderberg limestone_ 53 19.