DEPARTMENT OF THE INTERIOR UNITED STATES GEOLOGICAL SUEVEY GEORGE OTIS SMITH, DIRECTOR WATER-SUPPLY PAPER 232 UNDERGROUND WATER RESOURCES OF CONNECTICUT BY HEEBERT E. GREGOEY WITH A STUDY OF THE OCCURRENCE OF WATER IN CRYSTALLINE ROCKS BY E. E. ELLIS PROPERTY OF U.S. GEOLOGICAL SURVEY WASHINGTON GOVERNMENT PRINTING OFFICE 1909 CONTENTS. INTRODUCTION. ............................................................ 9 CHAPTER I. GEOGRAPHY. ................................................. 11 Topography........................................................... 11 General relations................................................... 11 Physiographic features............................................. 12 The highlands................................................. 12 The western highland...................................... 12 The eastern highland....................................... 14 Valleys in the highlands.................................... 14 Central lowland................................................ 16 Extent and character...................................... 16 Lava ridges................................................ 16 Farmington and Connecticut valley lowlands................ 17 Coast line..................................................... 17 Drainage.............................................................. 17 Forests................................................................ 20 Climate.............................................................. 20 Meteorological data................................................. 20 Summary.......................................................... 26 Surface-water supply.................................................. 27 Source and character............................................... 27 Quantity available................................................. 28 Population and industries.............................................. 30 CHAPTER II. GEOLOGY. ................................................... 31 Outline of geologic history.............................................. 31 Descriptive geology.................................................... 34 Introduction...................................................... 34 Crystalline rocks................................................... 35 Distribution and character...................................... 35 Joints........................................................ 37 Faults........................................................ 38 Triassic sandstone and trap......................................... 38 Distribution.................................................. 38 Stratigraphy.................................................. 38 Joints........................................................ 40 Faults........................................................ 41 Pleistocene drift................................................... 42 Distribution and general relations.............................. 42 Character of material........................................... 42 3 4 CONTENTS. Page. CHAPTER III. OCCURRENCE AND RECOVERY OP GROUND WATER. .......... 44 Circulation of ground water............................................. 44 The water table.................................................... 44 Movement of ground water........................................ 45 Porosity........................................................... 45 Permeability..................................................... 46 Artesian conditions. .............................................. 48 Springs........................................................... 50 Amount of ground water................................................ 51 Temperature of ground water.......................................... 52 Contamination........................................................ 53 CHAPTER IV. GROUND WATER IN THE CRYSTALLINE ROCKS or CONNECTICUT, by E. E. Ellis........................................................... 54 Introduction...............................^.......................... 54 Literature............................................................ 54 Distribution and character of crystalline rocks in Connecticut............ 56 Rock types........................................................ 56 Granite........................................................ 58 Gneiss......................................................... 58 Schist........................................................ 58 Quartzite schist............................................... 58 Pegmatite.................................................... 59 Trap rock..................................................... 59 Limestone.................................................... 59 Drilling products................................................... 59 Drift.............................................................. 60 Conditions affecting occurrence of water in crystalline rocks............. 60 Introduction...................................................... 60 Joints............................................................ 61 Vertical joints................................................ 61 Horizontal joints.............................................. 62 Relations of rock type to jointing.............................. 62 Joint direction................................................ 63 Structure planes............................................... 63 Variation in jointing........................................... 63 Faults............................................................ 65 Circulation and storage of water....................................... 65 Influence of joints and other openings. ............................ 65 Spacing of vertical joints...................................... 65 Spacing of horizontal joints.................................... 66 Continuity of horizontal joints................................. 66 Continuity of vertical joints................................... 67 Fissility and schistosity openings............................... 67 Intersection of fractures....................................... 67 Opening of joints............................................. 68 Number of contributory joints. ............................... 70 Water level. ..................................................... 70 Direction of circulation........................................... 72 Decomposition as a measure of circulation........................... 73 Storage of water................................................... 74 CONTENTS. 5 Page. CHAPTER IV. GROUND WATER IN THE CRYSTALLINE ROCKS OF CONNECTICUT, by E. E. Ellis Continued. Tabulated well records................................................. 77 Practical applications................................................. 91 Percentage of failure of wells....................................... 91 Variations in yield and depth...................................... 92 Limit of depth for wells in crystalline rocks......................... 93 Quality of water.................................................. 94 Temperature of water.............................................. 94 Location of wells................................................. 94 Constancy of yield................................................. 95 Flowing wells..................................................... 96 Wells in varying rock types........................................... 97 Wells in granite.................................................. 97 Wells in schist and gneiss......................................... 98 Wells in quartzite schist........................................... 99 Wells in phyllite................................................. 99 Wells in limestone................................................ 99 Wells in granodiorite.............................................. 100 Statistical tables...................................................... 101 CHAPTER V. GROUND WATER IN TRIASSIC SANDSTONES AND TRAPS. ........... 104 Introduction.......... ................................................ 104 Water within the rocks................................................ 104 Conditions of occurrence........................................... 104 In sandstone...................................................... 104 In conglomerate................................................... 106 In shales.......................................................... 106 In trap..........................J................................ 107 Water in bedding planes............................................... 107 Conditions of occurrence........................................... 107 Black shale....................... .............................. 109 Water in joints........................................................ 109 Vertical and horizontal joints....................................... 109 Direction and continuity of jointing............................... 112 Spacing of joints.................................................. 112 Opening of joints................................................. 113 Joints in trap..................................................... 113 Water along fault lines................................................. 114 Records of wells in Triassic sandstones, conglomerates, and shales......... 115 Wells in trap.......................................................... 128 Practical applications................................................. 130 Yield of wells.........................................:........... 130 Depth of wells..................................................