Geological maps: An Introduction

1 Some fundamentals of geological maps.- 1.1 Introduction.- 1.2 The topographic base map.- 1.2.1 Scale.- 1.2.2 Map projection.- 1.2.3 Grid systems and location.- 1.2.4 Relief.- 1.2.5 Key or legend.- 1.3 Geological aspects.- 1.3.1 Key or legend.- 1.3.2 Superficial and bedrock maps.- 1.3.3 The third dimension: geological cross-sections.- 1.3.4 The interpretive nature of maps.- 1.3.5 Aesthetics.- 1.4 Summary chapter.- 1.5 Selected further reading.- 2 The nature of geological maps: the Ten Mile map of the UK and the 1: 2 500 000 map of the USA.- 2.1 Introduction: cartographic matters.- 2.2 Interpretation of the maps: geology and relief.- 2.3 Map patterns and geological structure.- 2.3.1 Dipping formations.- 2.3.2 Unconformities.- 2.3.3 Folded rocks.- 2.3.4 Faulted rocks.- 2.3.5 Igneous rocks and geological histories.- 2.4 Conclusion.- 2.5 Summary of chapter.- 3 The three-dimensional aspect: structure contours.- 3.1 Introduction.- 3.2 The nature of structure contours.- 3.3 Examples of structure contours on maps.- 3.4 Structure contours derived from borehole/well information.- 3.5 Structure contours derived from topography: the theory.- 3.6 Structure contours derived from topography: the practice.- 3.7 Structure contours from topography and boreholes.- 3.8 Straight structure contours.- 3.9 Summary of chapter.- 3.10 Selected further reading.- 4 Measurements in three dimensions: strike and dip, formation thickness and depth.- 4.1 Introduction.- 4.2 Strike and dip.- 4.3 Apparent dip.- 4.4 Formation thickness.- 4.5 Formation depth.- 4.6 The ‘three-point’ method.- 4.7 Summary of chapter.- 4.8 Selected further reading.- 5 Geological cross-sections.- 5.1 Introduction.- 5.2 Line of section.- 5.3 Scale and vertical exaggeration.- 5.4 Manual drawing of cross-sections.- 5.5 Structure and stratigraphic sections.- 5.6 Three-dimensional diagrams.- 5.6.1 Fence diagrams.- 5.6.2 Block diagrams.- 5.7 Summary of chapter.- 5.8 Selected further reading.- 6 Visual assessment of outcrop patterns.- 6.1 Introduction.- 6.2 Horizontal formation.- 6.3 Dipping formations.- 6.3.1 Recognition.- 6.3.2 Assessment of formation dip in valleys.- 6.4 Vertical formations.- 6.5 Assessment of formation thickness.- 6.6 Summary of chapter.- 6.7 Exercises on visual assessment.- 7 Unconformities.- 7.1 Introduction.- 7.2 Terminology.- 7.3 Recognition on maps.- 7.4 Associated features.- 7.5 Use on maps.- 7.6 Palaeogeological maps.- 7.7 Summary of chapter.- 7.8 Selected further reading.- 8 Folds.- 8.1 Introduction.- 8.2 Description from maps.- 8.2.1 The parts of a fold.- 8.2.2 Fold orientation.- 8.2.3 Fold attitude.- 8.2.4 Fold shape.- 8.2.5 Fold style.- 8.2.6 Fold dimensions.- 8.3 Visual assessment on maps.- 8.4 Measurements on maps.- 8.5 Summary of chapter.- 9 Faults: the fundamentals.- 9.1 Introduction.- 9.2 Fault parts, orientation and dimensions.- 9.3 Fault displacement.- 9.4 Classification of faults.- 9.5 Visual assessment on maps.- 9.6 Measurements on maps.- 9.7 Summary of chapter.- 10 More on faults: contraction (thrust), extension, and strike-slip faults.- 10.1 Introduction.- 10.2 Contraction (thrust) faults.- 10.2.1 Characteristics.- 10.2.2 Recognition on maps.- 10.2.3 Three-dimensional arrangement.- 10.2.4 Displacement amount, direction and sequence.- 10.3 Extension faults.- 10.3.1 General.- 10.3.2 Characteristics.- 10.3.3 Extension faults on maps.- 10.4 Strike-slip faults.- 10.4.1 Characteristics.- 10.4.2 Recognition on maps.- 10.5 Summary of chapter.- 10.6 Selected further reading.- 11 Igneous and metamorphic rocks; mineral deposits.- 11.1 Introduction.- 11.2 Igneous rocks.- 11.2.1 Volcaniclastic rocks.- 11.2.2 Magmatic rocks.- 11.3 Metamorphic rocks.- 11.4 Mineral deposits.- 11.5 Summary of chapter.- 11.6 Selected further reading.- 12 Geological history from maps.- 12.1 Introduction.- 12.2 Sedimentary successions.- 12.3 Deformed rocks.- 12.4 Non-sedimentary rocks.- 12.5 Reading a geological map.- 12.6 Writing a map report.- 12.7 Summary of chapter.- 13 The production of geological maps.- 13.1 Introduction.- 13.2 The field survey.- 13.3 Preparation of maps for publication.- 13.3.1 Scale.- 13.3.2 Boundaries.- 13.3.3 Key and other information.- 13.3.4 Ornament.- 13.4.5 Colour.- 13.4 Map reports.- 13.5 Availability of maps.- 13.6 Conclusions.- 14 The heritage of geological maps.- 14.1 Introduction.- 14.2 A short history of geological maps.- 14.3 The contributions of some individuals.- 14.3.1 Jean Etienne Guettard (1715–86).- 14.3.2 William Smith (1769–1839).- 14.3.3 John MacCulloch (1773–1835).- 14.3.4 John Phillips (1800–74).- 14.3.5 John Wesley Powell (1834–1902).- 14.3.6 Sir Edward Bailey (1881–1965).- 15 Current trends in geological maps.- 15.1 Introduction.- 15.2 New technologies in geologicam mps.- 15.2.1 Field surveying.- 15.2.2 Remote sensing.- 15.2.3 Computer methods in map manipulation and production.- 15.2.4 Map storage, indexing and retrieval.- 15.3 New forms in geological maps.- 15.4 Specialised and thematic maps.- 15.5 Summary of chapter.- 15.6 Selected further reading.- References.