Jörn H. Kruhl is retired professor of geology at Technische Universität München, Germany. He received his Dr. rer. nat. from Rheinische Friedrich-Wilhelms-Universität Bonn and held appointments in research and teaching at universities in Mainz, Salzburg, Berlin and Frankfurt/M. For decades, he worked on rock structures in numerous regions and orogens, from macro to micro, in the field and at the microscope.

About the Author vii

Preface ix

1 Introduction 1

1.1 Why Do We Need Drawings? 5

1.2 The Tools 11

1.3 Sizes of Drawings 12

1.4 Geological Versus Artistic Drawing 13

1.5 Drawing With Symbols 15

1.6 Realistic Drawing 21

1.7 The Fractal Geometry of Geological Fabrics 26

1.8 Basic Rules of Geological Drawing 29

References 30

2 Rock Thin Sections 33

2.1 Drawing as a Form of Microscopy 35

2.2 Drawing with Various Tools 35

2.3 Foundations of Thin-Section Drawing 36

2.4 Minerals and Their Characteristic Fabrics Under the Microscope 41

2.5 Sketches for Fast Documentation 52

2.6 Development of Precise Thin-Section Drawings 60

2.7 Digital Reworking of Manual Thin-Section Drawings 82

2.8 Digital Drawing 83

Summary 90

References 93

3 Specimen Sections 95

3.1 The Geological Message of a Drawing 95

3.2 Schematic Representation of Minerals 97

3.3 Schematizing Rocks and their Structures 100

3.4 Development of Drawings 104

3.5 Illustration on Different Scales 107

3.6 Detailed Drawings of Sample Cuts 110

Summary 116

4 Drawing Rock Structures in Three Dimensions 117

4.1 Foundations 118

4.2 The Development of Schematic 3D Drawings 125

4.3 Field Drawing 156

4.4 Digital Processing 169

4.5 Rules of Labeling 172

Summary 174

References 177

5 Geological Stereograms 179

5.1 Foundations 179

5.2 Orientation and Extension 181

5.3 Additions and Labeling 189

5.4 Digital Processing 193

Summary 195

References 196

6 Solutions 199

Index 207