DEPARTMENT OF THE INTERIOR Ray Lyman Wilbnr, Secretary U. S. GEOLOGICAL SURVEY George Otis Smith, Director Bulletin 799 GEOLOGY OF THE McCALLS FEBEY-QUABBYVILLE DISTEICT PENNSYLVANIA BY ELEANORA BLISS KNOPF AND ANNA I. JONAS UNITED STATES GOVERNMENT FEINTING OFFICE WASHINGTON : 1929 ADDITIONAL COPIES OF THIS PUBLICATION MAY BE PROCURED FROM THE SUPERINTENDENT OF DOCUMENTS U. S. GOVERNMENT PRINTING OFFICE WASHINGTON, D. C. AT 35 CENTS PER COPY CONTENTS Pag* 1 Outline of report._._____-_-___--__-__-_--------_--_-.-_---_------- ix Introduction..___________________-__-____--_-_-_------------------ 1 * Location of the district__-___.____-_-_--------_-------------_-- 1 ^ Field work and acknowledgments.-___-__---____----_-_-_----_-- 3 Previous work_____-_-__-_-_------_-_-~----_---_--_-_-_------- 3 . Bibliography.._-------_---.------------------_------ ..---. 5 Geography __________-_-_-__-__-_-----_-_-_-------------_--------- 6 ; Topography.._-.-___-_______.___-_-_-__-_..__.-------____-_-- 6 Drainage __---_--.----_.-.---_-----_-_------------.---_------ 8 4 Climate.__.____.- ____-_--_--_--- -------- ----- 9 General geology-______------_---_--_---------__-_-_-------------- 10 Outline of the geology of the Appalachian Mountains and the Pied- _ mont province-------.-------------------------------------- 10 " Appalachian Mountains__-__--_-----_---_---------------_- 10 .j General features --_---_----_---_----_---------------- 10 Geology of the Reading Hills._._____-____-_--.-_-.-.___ 11 j Geology of Catoctin-South Mountain___________________ 13 Piedmont province-_-_--_--___--_-_-----------__--_----_-- 13 General geology of the Piedmont province in Pennsylvania. 14 Geology of the Piedmont upland in Maryland._.__.____.. 15 Baltimore gneiss.._.___--__--_--__-_-_--_--__-_.__ 15 Glenarm series.__--..__--_-__-._--_--._-_-._-_---___ 15 * Geology of the McCalls Ferry-Quarry ville district. ________________ 18 , Pre-Cambrian rocks of sedimentary origin..__________________ 18 Pre-Glenarm rocks of the Mine Ridge upland__.______._. 18 Baltimore gneiss._.___-__-_--__-____.-______----__ 18 Glenarm series in Pennsylvania._---______---.____-__.__ 24 Cockeysville marble.-.-.__________________________ 25 Wissahickon formation..______.____-___-__--__._-__ 25 * Oligoclase-mica schist f acies _-___-_.-_.____-.___ 25 Diaphthoritic schists.-_---___-__________._-___ 27 Albite-chlorite schist f acies _--___._-________-___ 28 Composition...-.-.....-._._.__...____...._-__ 30 Metamorphism..-----.-_----..__.-_-__._..._-_-_.__ 32 Age---.---------.-.-.-.-.-----..-...-........-.-.... 33 Peters Creek schist._______________________________ 35 m Cardiff conglomerate,__----_-__---.__.._____-_____ 37 Peach Bottom slate.______________________________ 39 Paleozoic sedimentary rocks.-__._-___-.__.____-__._________ 41 Paleozoic stratigraphy of Welsh Mountain and vicinity.... 41 ,t Paleozoic stratigraphy of Mine Ridge upland and vicinity._ 42 Lower Cambrian rocks of the McCalls Ferry-Quarry ville dis- trict..-----._---_-_-..---------_----_---_-______._ 42 L Chickies quartzite.________._-_____________________ 42 Hellam conglomerate member-____.______.._____ 43 Quartzite member-______-_-__._____-.___-_--__ 44 Harpers and Antietam schists.............___..__.__ 45 in IV CONTENTS General geology Continued. Geology of the McCalls Ferry-Quarryville district Continued. Paleozoic sedimentary rocks Continued. Lower Cambrian rocks of the McCalls Ferry-Quarryville district Continued. Page Vintage dolomite.-________________-____-_-____- 50 Kinzers formation._______________________________ 52 Ledger dolomite.____________________-_--_-____- 53 Ordovician rocks.__.__________-________-____---___-_ 54 Conestoga limestone____-__-_-__-_______-_-____--__ 54 Igneous rocks.------------------ ,__________-____-_--__ 58 Pre-Cambrian igneous rocks.________________---__------ 59 Biotitie amphibolite schists.----------------------- 59 4 Metagabbro---_-----_--_-_-__.______-___--__- 59 Age of biotitic amphibolite schist and metagabbro.---- 60 Serpentine.._______----____-__-_____---_----_---_ 61 ^ Amphibolite and chlorite schist altered volcanic flows. 62 * Igneous rocks of undetermined pre-Triassic age ___________ 62 Quartz monzonite-____-________-_-_____-_____._- 62 Quartz monzonite pegmatite and aplite_____-_____-_- 63 ^ Quartz diorite-_-___-_-_____-__-____----___--_--_- 64 * Granitic pegmatite and granite____------____--__-_- 64 \_ Age of granite and quartz monzonite_____^____.____- 65 Triassic igneous rocks______--__-_____-----_--_--_---- 67 l.._ Diabase _________________________________________ 67 Correlation of rocks of McCalls Ferry-Quarryville district with those of other areas-_-_-__-____-__--_-___-_--_--_______- 68 Structure _________________________________________________________ 71 Folds........... ---_-------_--_----_-__-_-__ _-_-_--__- 71 Faults___--_-__-_-------._-_--_-__-_._________--_--_-___ 74 Age of the structure_--_---_-----_____-__.____-___--__-______-_ 77 Pre-Cambrian folding.___-___-_______-__________,______-_--_-_ 77 Paleozoic folding and faulting_________ __..______ ___... 77 Age of the Martic overthrust.__________________________________ 79 Close folding of Mine Ridge anticline.___________________________ 80 Load.-.--.--.-----_-----_-___---_-______-____-----_-_--_-.. 80 Triassic structural features_____________'_-_______-_____-________ 81 ^ Geologic history._______ _________ ___ _______ -__._____ 81 Stratigraphic record___________________________________________ 81 Pre-Cambrian history____________________________________ 81 Paleozoic history_____--________-___________-_______-______ 85 General outline-____-__-_-________-_______--__-_-_-___ 85 Age of the post-Conestoga deformation and metamorphism. _ 86 Inferences drawn from the post-Chazy stratigraphy of 0 adjoining regions----__-___-_-______-_--_-___.___ 86 Inferences drawn from the probable method of develop­ ment of observed structure-____________----_-____ 88 Summary of Paleozoic geologic history.._________________ 89 r' Post-Paleozoic stratigraphic record __________________________ 90 Physiographic record________________________________________ 91 Evidence of former drainage courses..____________----_-____-_ 91 > Superimposition_____________________________________ 92 , Cross profiles of stream valleys_______________-__-_.____ 94 Wind gaps__.________________________________________ 94 Longitudinal profiles of streams...--__-______--_________ 95 CONTENTS V Geologic history Continued. Physiographic record Continued. Page Relative preservation of successive drainage courses__----_---_ 95 Study of interstream areas.______ _______________________ 96 Study of drainage modifications.____________________________ 100 Mine Ridge cycle of erosion______________._____________ 100 Honeybrook subcycle of erosion___._____________________ 103 Harrjglburg subcycle of erosion.._.__-______-___-____.___ 103 Bryn Mawr subcycle of erosion.________________________ 104 Brandywine subcycle of erosion_________________________ 105 Late Pleistocene erosion______________________________ 109 Significance of knickpoints in stream gradient________________ 109 Longitudinal profiles of Susquehanna River and minor streams.. 110 Sequence and correlation of erosion records.__________________ 116 Amount and duration of erosion____ __ ______________ 117 Periodicity of uplift.__-_-_______-_-___----_____ _________ 117 Age of erosion cycles._____________________________________ 118 Origin of metamorphism in the crystalline schists of the Piedmont province . 118 Variable metamorphic intensity in the McCalls Ferry-Quarryville district. ________.._________________.._____----. 118 Previous ideas on me'tamorphism of the Piedmont province.. _______ 119 Criteria for determination of metamorphic intensity____-____-__-__ 120 Metamorphic textures_-_____---__----_---___-__._---__--_- 121 Metamorphic minerals.______--___---__--___--__--_-___-__- 122 Progressive metamorphism-________________________________ 122 Retrogressive metamorphism-_____---__--___-_--__--_-----_ 124 Regional variation in metamorphic intensity..___________.__...___ 124 Early pre-Cambrian paragneisses (Baltimore gneiss).-__.__-_ 124 Later pre-Cambrian paragneisses (Glenarm series)___________ 125 Paleozoic rocks of sedimentary origin _______________________ 125 Causes of regional variation in metamorphic intensity..____.._____- 128 Causes of regional metamorphism.__________________________ 129 Dynamic and contact metamorphism in the oldest pre-Cam­ brian rocks-__---___--_-_-_________-_-__-__--_-____---_ 130 Load metamorphism and regionaj. contact metamorphism in the Glenarm series____---_---______-__-_--__-__-_-____---_ 131 Double metamorphism in the Glenarm series_.___--_-___--___ 132 Variation in metamorphic intensity in the Paleozoic rocks...--. 132 Double metamorphism in the Paleozoic rocks.________________ 133 Development of older metamorphism in the Glenarm series and in Paleozoic rocks._____________________________________ 134 Relative age of double metamorphism in the Glenarm series and in the Paleozoic rocks__________________________________ 138 Summary of conclusions___--_-_--_____--___-______-___-______- 139 Economic geology.________________________________________________ 141 Nickel ore.___________________________________________________ 141 Iron ore________________________________.-____--_____. 150 Chrome ore._________________________________________________ 151 Silver ore.-_--_-____-____---___--_-_--______-_______-_____-__ 152 Roofing slate_--___-_-_-__-_--__--------__-______----___---_ 152