Contents

I. Introduction     1
Values of Geology, 1; Contents of This Book, 1; General Principles of Historical Interpretation, 2; Major Rock Types and the Rock Cycle, 2; Summary, 12.

II. Earth History and Geologic Time     13
The Sense of Time, 13; Relative Geologic Time, 13; The Geologic Time Scale, 15; Relative Dating of Igneous Rocks, 16; Absolute Time, 18; Summary, 22.

III. General Geologic Setting of Michigan     23
The Broad Picture, 23; The Continental Interior in the Paleozoic, 25; The Paleozoic Geosynclines, 25; A Basin beneath the State, 26; The Plastic Earth, 28; The Earth's Interior, 29.

IV. Precambrian Eras     31
Introduction, 31; Precambrian in Michigan, 38; Iron Ores of Michigan, 61; Keweenaw Copper, 70; White Pine Copper, 77; The Role of Hypotheses in Geology, 79.

V. The Paleozoic---Era of Inland Seas     81
Introduction, 81; The Paleozoic Rock Record in Michigan, 83; The Cambrian Period---Beginning of the Paleozoic Era, 91; The Ordovician Period, 98; The Silurian Period, 102; The Devonian Period, 113; The Mississippian Period, 123; The Pennsylvanian Period, 126; Paleozoic Era---Conclusion and Summary, 134.

VI. The Lost Interval     136

VII. The Pleistocene (Ice Age) Epoch     141
Nature of Glacial Ice, 141; The Work of Ice, 147; General History of the Pleistocene, 158; The Pleistocene in Michigan, 159.

VIII. The Great Lakes in Late Glacial and Postglacial Time     164
Introduction, 164; The Proglacial Lake Sequence, 168; The Record from Mackinac Island, 176.

IX. Water and Wind in Michigan     180
Introduction, 180; Water Use, 180; The Hydrologic Cycle, 181; Water Underground, 182; Extraction of Water from the Ground, 184; The Search for Ground Water, 184; Some Ground Water Problems in Michigan, 185; The Work of Ground Water in the State, 185; Surface Waters in General, 187; Rivers and Streams, 187; Inland Lakes and Swamps, 191; Surface Water Conservation Problems, 198; Wind, 198; Shoreline Processes in General, 205; Waves and Shore Currents, 205; Shore Features, 208; The Herring Lakes---A Case History of Dunes and Bars, 213; The Southeastern Lake Michigan Shore, 217.

X. Petroleum and Natural Gas in Michigan     228
Introduction, 228; Origin and Source, 228; Migration Through the Rocks, 229; Reservoir Rocks, 230; Seals and Traps, 231; Petroleum Exploration, 234; Production of Oil and Gas, 235; Oil and Gas in Michigan, 237; History of Michigan Oil and Gas Production, 237; Geology of Michigan Oil and Gas, 237; Reservoir Rocks in Michigan, 239; Oil and Gas Fields in Michigan, 241; Summary, 243.

XI. Minerals in Michigan     244
Introduction, 244; Nature of Minerals, 244; Methods of Mineral Study, 245; Physical Properties of Minerals, 247; Mineral Collecting in Michigan, 241; Lower Peninsula Localities and Exhibits, 254; Upper Peninsula Localities and Exhibits, 258; List of Michigan Minerals, 262.

XII. Rocks     265
Introduction, 265; Main Rock Types, 265; Rock Textures, 265; Rock Identification, 268; Igneous Rocks, 269; Metamorphic Rocks, 269; Sedimentary Rocks, 272.

XIII. Fossil Invertebrates     285
Introduction, 285; Definition of a Fossil, 285; Types of Fossil Preservation, 285; Naming and Studying Fossils, 287; Classification of Fossil and Living Invertebrate Animals, 288; The Significance of Fossils, 309; Geological Uses of Fossils, 310; Fossils and Ancient Environments, 333; Michigan Fossil-Collecting Localities, 344.

XIV. Fossil Vertebrates in Michigan     350
Introduction, 350; Relative Abundance of Fossil Vertebrates, 350; Problems of Identification and Restoration, 351; Finding Fossil Vertebrates in Michigan, 352; Special Problems, 353; Documentation of the Michigan Record, 354; The Value of Fossil Vertebrates, 354; General References, 355; General Geologic History and Evolution of Vertebrates, 355; Fossil Vertebrate Faunas of Michigan and Their Ancient Environments, 363; Middle Devonian Faunas, 365; Late Devonian Vertebrate Faunas, 366; Early Mississippian Vertebrate Faunas, 366; Pennsylvanian Vertebrate Faunas of Michigan, 367; Pleistocene and Post-Pleistocene Vertebrate Faunas of Michigan, 371; Early Man in Michigan, 388; Detailed List of Fossil Vertebrates from Michigan, 389.

XV. Fossil Plants in Michigan     416
Introduction, 416; General Review of Plant History, 416; Precambrian Plant Remains in Michigan, 417; Paleozoic Fucoids, 423; Devonian Plants, 423; Mississippian Plants, 425; Coal Swamp Floras of the Pennsylvanian Period, 426; Mesozoic Floras, 439; Post-Pleistocene Floras of Michigan, 441; Summary of the Fossil Record of Plants in Michigan, 449.

Bibliography     451
Index     459