UNITED STATES DEPARTMENT OF THE INTERIOR Ray Lyman Wilbur, Secretary GEOLOGICAL SURVEY George Otis Smith, Director Bulletin 828 GEOLOGY AND MINERAL RESOURCES OF THE QUAKERTOWN-DOYLESTOWN DISTRICT PENNSYLVANIA AND NEW JERSEY BY F. BASCOM, E. T. WHERRY, G. W. STOSE and A. I. JONAS UNITED STATES GOVERNMENT PRINTING OFFICE WASHINGTON : 1931 For sale by the Superintendent of Documents, Washington, D. C. - - - - Price 40 cents CONTENTS Page Introduction. _ __ _______________________________________________ 1 Location and general relations of the area. _______________________ 1 General geography and geology of the region _____________________ 1 Appalachian Highlands______-________-________--__________ 1 , Piedmont province____-_-__-________-______--__ ________ 2 Geography _______________________________________________________ 7 Surface features. _ _____________________________________________ 7 Drainage...____-_______--_ ___________________________________ 8 Population, climate, vegetation, and culture____-__-______________ 9 Descriptive geology. _________________ _ __________ _ _____ _ __ _ 11 Stratigraphy ___ __________--________--_-___-__--_---_--_---__ 11 Archean system_____-___________________-_________________ 11 Sedimentary rocks________________________-_____._____ 11 Graphitic gneiss_-_--__----___--_------------_--___ 11 Pre-Cambrian igneous rocks. ______ _________________________ 13 General features_____-____-__--___-----------_--_-__-_ 13 Quartz monzonite. _________________ ^_ _________________ 13 Gabbro. _--__-___-_-__--_--__-____--------_-_---_-_-_ 15 Pegmatite _ _________________________________________ 17 Cambrian system-___-___-_____-__-_____-__--_-___-__--.__ 17 Hardyston quartzite_-__-----__--_------------_-___-___ 17 Tomstown dolomite___-__--___--_--_-___-__--_-__-____ 19 Elbrook limestone _ __________________________________ 20 Conococheague limestone. _____________________________ 21 Ordovician system. _______________________________________ 22 Beekmantown (?) limestone. _ ________-__---_-__-_-_-___ 22 Cocalico phyllite_-__-__--_--_____--_-----___-__---____ 23 Triassic 8ystem_________________________-__-___-__-_______ 24 Sedimentary rocks__________-_________----__-_-----.__ 24 Newark group. _-_____-___-_____----___--__-_--___ 24 General features______________________________ 24 Stockton formation--_____-_--__---_--__--_____ 25 Lockatong formation_______________.__________ 27 Brunswick formation__________________________ 30 Igneous rocks---___------_-_-_---------_.--_-_---_-___- 35 Diabase. _ _______________--__--_---___---_-_---___ 35 Quaternary system. _____-_--______--_--_---_-----_------__ 39 Mountain wash_ ______-__________--_---_-__--.-__--__- 39 Alluvium __ -__--_--__-__--__ _ _ _ _ __ ________ _ 39 Structure. ___-____-____---_-_____--_____-______----_------___ 39 Pre- Triassic rocks. _____--___-_____-__--__-------__----_-_- 39 Northwest corner of the area______-___-__-___-__-_--___ 39 East of Doylestown___________________________________ 40 Triassic rocks-__-____--_--__----__------_--_---------_-__- 41 Folds. _________________________ _ _______ 41 Faults. _____ ____ _ __________ --_ __ -_ ___ ___ 42 in IV CONTENTS Page Historical geology____________________________________________ _ 44 Pre-Cambrian sedimentation and intrusion.______________________ 44 Cambrian and Ordo vician sedimentation _________________________ 45 Silurian and Devonian periods_-____-_____________-__-__________ 45 Late Paleozoic folding and uplift..______________________________ 46 Triassic sedimentation, intrusion, and faulting.___________________ 47 Posfr-Triassic uplift and erosion_________________________________ 48 Economic geology_________________________________________________ 49 Building stone________________________________________________ 49 Road metal.--_--______--__--_---__-_----------_-_-__--__l-__ 50 Limestone ____________________________________________________ 51 Sand and gravel-___-_-------_----------------------__--__--__ 52 Iron ore and umber. ________----____-_---__--_--_____N_____-___ 52 Copper ______________________________________________________ 52 Gold. ___-_------.______-.._______________________ 53 Soils_____-_.-___-_______-______________ __-_.__ 53 Water resources_____________________________________________ 56 Surface water_____________________________________________ 56 Ground water.___________________________________________ 56 Town water supplies____________________________________ 58 Index________-__-__--_---_____--_---_---_-_-_--_---__--_.._ ______ 61 ILLUSTRATIONS Page PLATE 1. Geologic map and sections of the Quakertown-Doylestown CllSTlrlC v _-*_»-_ -,_ _.-._ -. -_ _, _ ______ -.-.-.___.-.-.-._ 2. Columnar section of the rocks of the Quakertown-Doylestown district._ ___-___-_____-_-----_______-_---__-___________ 12 3. A, Diabase weathering into rounded boulders by exfoliation, Philadelphia & Reading Railway cut at Rock Hill, Quaker- town quadrangle; B, Cryptozoon proliferum, fossil algae in Conococheague limestone, Bycot, Doylestown quadrangle____ 28 4. A, Well-bedded shales of the Lockatong formation in quarry on Delaware River 1 mile west of Lumberville, Doylestown quadrangle; B, Fossil leaf of Cycadites sp. from the Stockton formation near Holicong, Doylestown quadrangle; C, Kettle Rock, a large hole resembling a pothole formed in hard dia­ base on Spring Mountain, Quakertown quadrangle._________ 29 FIGURE 1. Index map of eastern Pennsylvania, western New Jersey, and parts of Delaware and Maryland________________________ 2 2. Map of the northern Appalachian Highlands, showing physio­ graphic divisions and relations to the Atlantic Plain.________ 3 3. Axes of structure of the Triassic beds in the Quakertown quadrangle ___---__--_----------___-_________-________ 42 GEOLOGY AND MINERAL RESOURCES OF THE QUAKERTOWN-DOYLESTOWN DISTRICT, PENNSYLVANIA AND NEW JERSEY 1 By F. BASCOM, E. T. WHERRY, G. W. STOSE, and A. I. JONAS INTRODUCTION By P. BASCOM LOCATION AND GENERAL RELATIONS OF THE AREA The Quakertown and Doylestown quadrangles, in this bulletin called the Quakertown-Doylestown district, lie mainly between the Delaware and Schuylkill Rivers, in southeastern Pennsylvania, north of Philadelphia; the northeast corner of the Doylestown quadrangle, inclosed by the Delaware River, embraces a small portion of western New Jersey northwest of Trenton. (See fig. 1.) The area lies chiefly in Bucks County but includes portions of Montgomery and Lehigh Counties, Pa., and a small part of Hunterdon County, N. J. This area as shown on the map (pi. 1) extends from latitude 40° 15' to 40° 30' N. and from longitude 75° to 75° 30' W. and includee one-eighth of a " square degree " of the earth's surface, which in this latitude amounts to 455 square miles. The district lies almost wholly in the Piedmont Lowlands of the Piedmont province; the extreme northwest corner of the Quaker- town quadrangle is part of an upland region which is regarded as a southern extension of the New England Upland and has been called the Reading prong of the New England Upland. In Pennsylvania this lowland area adjoins on the southeast the Piedmont Upland of the Piedmont province, and in New Jersey it adjoins in this direction the Atlantic Plain with no intervening upland. GENERAL GEOGRAPHY AND GEOLOGY OP THE REGION Appalachian Highlands. The eastern section of the United States is separable into two great natural divisions the Atlantic Plain, bordering the sea with a maximum width of 250 miles and extending beneath the sea to the edge of the continental plateau, 1 The Triassic sedimentary rocks were surveyed by E. T. Wherry and the Triassic diabase and pre-Cambrian rocks by Eleanora Bliss [KnopfJ and Anna I. Jonas, the preliminary survey of the Paleozoic rocks was made chiefly by F. Bascom and E. T. Wherry and the final survey by G. W. Stose. F. Bascom was in. charge of the field work and inspected the results. 1 2 QUAKERTOWN-DOYLESTOWF DISTRICT, PA.-N. J. and the Appalachian Highlands, extending from the Atlantic Plain to the Mississippi lowlands and from Canada to the Gulf plains. The Appalachian Highlands (see fig. 2) embrace seven physio­ graphic provinces, of which the most easterly the Piedmont adjoins the Atlantic Plain and includes the area described in this bulletin. This province is separated from the valley and moun­ tains of the western Appalachian Highlands on the southwest by FIGURE 1. Index map of eastern Pennsylvania, western New Jersey, and parts of Delaware and Maryland. The location of the Quakertown and Doylestown quad­ rangles is shown by the darker ruling. Other quadrangles, indicated by lighter ruling, are described in Geologic Folios 70, Washington; 83, New York City; 137, Dover; 152, Patuxent; 157, Passaic; 182, Choptank;'161, Franklin Furnace; 162, Philadelphia; 167, Trenton; 191, Raritan; 204, Tolchester; 211, Elkton-Wilming- ton; 225, Fairfield-Gettysburg; and in Bull. 799, Geology of the McCalls Ferry- Quarryville district, Pa. the Blue Ridge province and on the northeast by a series of upland plateaus that stretch away to the east. Piedmont province. The Piedmont province owes its name to its location at the eastern foot of the Appalachian Mountains and in­ cludes the Piedmont Upland and the Piedmont Lowlands. North­ eastward it merges into the New England Upland and southwest- ward it passes into the Coastal Plain. The province curves parallel to the Atlantic coast, with a mean width of 60 miles and a maximum width in its central portion of 120 miles. GENERAL GEOGRAPHY AND GEOLOGY OF THE REGION" 3 The lowlands