Earth Structure: An Introduction to Structural Geology and Tectonics (Second Edition)

by Van Der Pluijm, Ben A; Marshak, Stephen

• ISBN13: 9780393924671
• ISBN10: 039392467X
• Edition: 2nd
• Format: Hardcover
• Copyright: 2003-12-29
• Publisher: W. W. Norton & Company

Summary

The Second Edition also benefits from new artwork that clearly illustrates complex concepts. New to the Second Edition:New Chapter: 15, "Geophysical Imaging," by Frederick Cook Within Chapters 21 and 22, four new essays on "Regional Perspectives" discuss the European Alps, the Altaids, the Appalachians, and the Cascadia Wedge. New and updated art for more informative illustration of concepts. The Second Edition now has 570 black & white figures.

Table of Contents

Preface	xv
PART A FUNDAMENTALS	1	(112)
Overview	2	(12)
Introduction	2	(2)
Classification of Geologic Structures	4	(2)
Stress, Strain, and Deformation	6	(2)
Structural Analysis and Scales of Observation	8	(2)
Some Guidelines for Structural Interpretation	10	(2)
Closing Remarks	12	(2)
Additional Reading	12	(2)
Primary and Nontectonic Structures	14	(26)
Introduction	14	(1)
Sedimentary Structures	14	(12)
The Use of Bedding in Structural Analysis	16	(1)
Graded Beds and Cross Beds	17	(2)
Surface Markings	19	(1)
Disrupted Bedding	19	(1)
Conformable and Unconformable Contacts	19	(4)
Compaction and Diagenetic Structures	23	(1)
Penecontemporaneous Structures	24	(2)
Salt Structures	26	(4)
Why Halokinesis Occurs	26	(1)
Geometry of Salt Structures and Associated Processes	27	(2)
Gravity-Driven Faulting and Folding	29	(1)
Practical Importance of Salt Structures	30	(1)
Igneous Structures	30	(5)
Structures Associated with Sheet Intrusions	31	(1)
Structures Associated with Plutons	32	(1)
Structures Associated with Extrusion	33	(2)
Cooling Fractures	35	(1)
Impact Structures	35	(3)
Closing Remarks	38	(2)
Additional Reading	38	(2)
Force and Stress	40	(22)
Introduction	40	(2)
Units and Fundamental Quantities	42	(1)
Force	43	(1)
Stress	44	(1)
Two-Dimensional Stress: Normal Stress and Shear Stress	44	(1)
Three-Dimensional Stress: Principal Planes and Principal Stresses	45	(3)
Stress at a Point	46	(1)
The Components of Stress	46	(1)
Stress States	47	(1)
Deriving Some Stress Relationships	48	(1)
Mohr Diagram for Stress	49	(3)
Constructing the Mohr Diagram	50	(1)
Some Common Stress States	51	(1)
Mean Stress and Deviation Stress	52	(1)
The Stress Tensor	53	(1)
A Brief Summary of Stress	54	(1)
Stress Trajectories and Stress Fields	55	(1)
Methods of Stress Measurement	56	(4)
Present-Day Stress	56	(1)
Paleostress	57	(1)
Stress in Earth	57	(3)
Closing Remarks	60	(2)
Additional Reading	60	(2)
Deformation and Strain	62	(28)
Introduction	62	(1)
Deformation and Strain	63	(2)
Homogenous Strain and the Strain Ellipsoid	65	(1)
Strain Path	66	(1)
Coaxial and Non-Coaxial Strain Accumulation	67	(2)
Superimposed Strain	69	(1)
Strain Quantities	70	(3)
Longitudinal Strain	70	(1)
Volumetric Strain	71	(1)
Angular Strain	71	(1)
Other Strain Quantities	71	(2)
The Mohr Circle for Strain	73	(2)
Strain States	75	(1)
Representation of Strain	75	(3)
Orientation	75	(1)
Shape and Intensity	76	(2)
Finite Strain Measurement	78	(11)
What Are We Really Measuring in Strain Analysis	79	(2)
Initially Spherical Objects	81	(1)
Initially Nonspherical Objects	82	(1)
Center-to-Center Method	83	(1)
Rf/Φmethod	83	(1)
Objects with Known Angular Relationships or Lengths	84	(1)
Angular Changes	84	(1)
Length Changes	85	(1)
Rock Textures and Other Strain Guages	86	(1)
What Do We Learn from Strain Analysis?	87	(2)
Closing Remarks	89	(1)
Additional Reading	89	(1)
Rheology	90	(23)
Introduction	90	(2)
Strain Rate	91	(1)
General Behavior: The Creep Curve	92	(1)
Rheologic Relationships	93	(7)
Elastic Behavior	93	(3)
Viscous Behavior	96	(1)
Visoelastic Behavior	97	(1)
Elastico-Viscous Behavior	97	(1)
General Linear Behavior	98	(1)
Nonlinear Behavior	98	(2)
Adventures with Natural Rocks	100	(8)
The Deformation Apparatus	101	(1)
Confining Pressure	102	(1)
Temperature	103	(1)
Strain Rate	104	(1)
Pore-Fluid Pressure	105	(1)
Work Hardening---Work Softening	106	(1)
Significance of Experiments to Natural Conditions	107	(1)
Confused by the Terminology?	108	(3)
Closing Remarks	111	(2)
Additional Reading	112	(1)
PART B BRITTLE STRUCTURES	113	(90)
Brittle Deformation	114	(24)
Introduction	114	(1)
Vocabulary of Brittle Deformation	114	(3)
What is Brittle Deformation?	117	(1)
Tensile Cracking	118	(5)
Stress Concentration and Griffith Cracks	118	(3)
Exploring Tensile Crack Development	121	(1)
Modes of Crack-Surface Displacement	122	(1)
Processes of Brittle Faulting	123	(1)
Slip by Growth of Fault-Parallel Veins	123	(1)
Cataclasis and Cataclastic Flow	123	(1)
Formation of Shear Fractures	124	(2)
Predicting Initiation of Brittle Deformation	126	(6)
Tensile Cracking Criteria	126	(1)
Shear-Fracture Criteria and Failure Envelopes	127	(5)
Frictional Sliding	132	(2)
Frictional Sliding Criteria	132	(1)
Will New Fractures Form or Will Existing Fractures Slide?	133	(1)
Effect of Environmental Factors in Failure	134	(2)
Effect of Fluids on Tensile Crack Growth	134	(2)
Effect of Dimensions on Tensile Strength	136	(1)
Effect of Pore Pressure on Shear Failure and Frictional Sliding	136	(1)
Effect of Intermediate Principal Stress on Shear Rupture	136	(1)
Closing Remarks	136	(2)
Additional Reading	137	(1)
Joints and Veins	138	(28)
Introduction	138	(2)
Surface Morphology of Joints	140	(4)
Plumose Structure	140	(1)
Why Does Plumose Structure Form?	141	(3)
Twist Hackle	144	(1)
Joint Arrays	144	(5)
Systematic versus Nonsystematic Joints	144	(1)
Joint Sets and Joint Systems	145	(1)
Cross-Cutting Relations Between Joints	146	(1)
Joint Spacing in Sedimentary Rocks	147	(2)
Joint Studies in the Field	149	(3)
Dealing with Field Data About Joints	150	(2)
Origin and Interpretation of Joints	152	(6)
Joints Related to Uplift and Unroofing	152	(1)
Formation of Sheeting Joints	153	(1)
Natural Hydraulic Fracturing	154	(1)
Joints Related to Regional Deformation	155	(1)
Orthogonal Joint Systems	156	(1)
Conjugate Joint Systems	157	(1)
Joint Trend as Paleostress Trajectory	158	(1)
Limits on Joint Growth	158	(1)
Veins and Vein Arrays	159	(4)
Formation of Vein Arrays	160	(1)
Vein Fill: Blocky and Fibrous Veins	160	(2)
Interpretation of Fibrous Veins	162	(1)
Lineaments	163	(1)
Closing Remarks	163	(3)
Additional Reading	165	(1)
Faults and Faulting	166	(37)
Introduction	166	(3)
Fault Geometry and Displacement	169	(10)
Basic Vocabulary	169	(3)
Representation of Faults on Maps and Cross Sections	172	(2)
Fault Separation and Determination of Net Slip	174	(2)
Fault Bends	176	(1)
Fault Terminations and Fault Length	177	(2)
Characteristics of Faults and Fault Zones	179	(8)
Brittle Fault Rocks	179	(3)
Slickensides and Slip Lineations	182	(2)
Subsidiary Fault and Fracture Geometries	184	(1)
Fault-Related Folding	184	(3)
Shear-Sense Indicators of Brittle Faults--A Summary	187	(1)
Recognizing and Interpreting Faults	187	(4)
Recognition of Faults from Subsurface Data	189	(1)
Changes in Fault Character with Depth	190	(1)
Relation of Faulting to Stress	191	(4)
Formation of Listric Faults	192	(1)
Fluids and Faulting	192	(1)
Stress and Faulting---A Continuing Debate	193	(2)
Fault Systems	195	(3)
Geometric Classification of Fault Arrays	195	(1)
Normal Fault systems	196	(1)
Reverse Fault Systems	196	(1)
Strike-Slip Fault Systems	197	(1)
Inversion of Fault Systems	197	(1)
Fault Systems and Paleostress	197	(1)
Faulting and Society	198	(3)
Faulting and Resources	199	(1)
Faulting and Earthquakes	199	(2)
Closing Remarks	201	(2)
Additional Reading	201	(2)
PART C DUCTILE STRUCTURES	203	(132)
Ductile Deformation Processes	204	(34)
Introduction	204	(2)
Cataclastic Flow	206	(1)
Crystal Defects	207	(3)
Point Defects	207	(1)
Line Defects or Dislocations	207	(3)
Crystal Plasticity	210	(7)
Dislocation Glide	210	(1)
Cross-Slip and Climb	210	(3)
Mechanical Twinning	213	(3)
Strain-Producing versus Rate-Controlling Mechanisms	216	(1)
Where Do Dislocations Come From?	216	(1)
Diffusional Mass Transfer	217	(2)
Volume Diffusion and Grain-Boundary Diffusion	218	(1)
Pressure Solution	218	(1)
Constitutive Equations or Flow Laws	219	(1)
A Microstructural View of Laboratory Behavior	220	(1)
Imaging Dislocations	221	(1)
Deformation Microstructures	222	(7)
Recovery	222	(3)
Recrystallization	225	(1)
Mechanisms of Recrystallization	226	(2)
Superplastic Creep	228	(1)
Deformation Mechanism Maps	229	(5)
How to Construct a Deformation Mechanism Map	232	(1)
A Note of Caution	233	(1)
Closing Remarks	234	(4)
Additional Reading	234	(2)
Appendix: Dislocation Decoration	236	(2)
Folds and Folding	238	(32)
Introduction	238	(1)
Anatomy of a Folded Surface	239	(4)
Fold Facing: Antiform, Synform, Anticline, and Syncline	241	(2)
Fold Classification	243	(3)
Fold Orientation	244	(1)
Fold Shape in Profile	245	(1)
Fold Systems	246	(4)
The Enveloping Surface	247	(1)
Folds Symmetry and Fold Vergence	248	(2)
Some Special Fold Geometries	250	(2)
Superposed Folding	252	(5)
The Priciple of Fold Superposition	252	(2)
Fold Interference Patterns	254	(1)
Fold Style	255	(2)
A Few Philosophical Points	257	(1)
The Mechanics of Folding	257	(5)
Passive Folding and Active Folding	257	(2)
Buckle Folds	259	(3)
Folded Multilayers	262	(1)
Kinematic Models of Folding	262	(4)
Flexural Slip/Flow Folding	262	(1)
Neutral-Surface Folding	263	(1)
Shear Folding	264	(1)
Fold Shape Modification	265	(1)
A Natural Example	265	(1)
A Possible Sequence of Events	266	(2)
Closing Remarks	268	(2)
Additional Reading	269	(1)
Fabrics: Foliations and Lineations	270	(24)
Introduction	270	(1)
Fabric Terminology	270	(2)
Foliations	272	(12)
What is Cleavage?	273	(1)
Disjunctive Cleavage	274	(3)
Pencil Cleavage	277	(1)
Slaty Cleavage	278	(1)
Phyllitic Cleavage and Schistosity	278	(2)
Crenulation Cleavage	280	(2)
Gneissic Layering and Migmatization	282	(2)
Mylonitic Foliation	284	(1)
Cleavage and Strain	284	(1)
Foliations in Folds and Fault Zones	285	(3)
Lineations	288	(4)
Form Lineations	288	(1)
Surface Lineations	289	(1)
Mineral Lineations	290	(1)
Tectonic Interpretation of Lineations	290	(2)
Other Physical Properties of Fabrics	292	(1)
Closing Remarks	292	(2)
Additional Reading	293	(1)
Ductile Shear Zones, Textures, and Transposition	294	(22)
Introduction	294	(2)
Mylonites	296	(2)
Type Mylonites	297	(1)
Shear-Sense Indicators	298	(6)
Plane of Observation	298	(1)
Grain-Tail Complexes	299	(1)
Fractured Grains and Mica Fish	299	(3)
Foliations: C-S and C-C' Structures	302	(1)
A Summary of Shear-Sense Indicators	303	(1)
Strain in Shear Zones	304	(3)
Rotated Grains	304	(1)
Deflected Foliations	305	(2)
Textures or Crystallographic-Preferred Fabrics	307	(4)
The Symmetry Principle	308	(2)
Textures as Shear-Sense Indicators	310	(1)
Fold Transposition	311	(2)
Sheath Folds	313	(1)
Closing Remarks	313	(3)
Additional Reading	315	(1)
Deformation, Metamorphism, and Time	316	(19)
Introduction	316	(1)
Field Observations and Study Goals	316	(3)
Pressure and Temperature	319	(3)
Status Report I	321	(1)
Deformation and Metamorphism	322	(3)
Status Report II	324	(1)
Time	325	(4)
The Isochron Equation	325	(2)
The Isotopic Closure Temperature	327	(1)
Dating Deformation	328	(1)
Status Report III	329	(1)
D-P-T-t Paths	329	(4)
Temperature-Time (T-t) History	331	(1)
Pressure-Temperature (P-T) History	331	(1)
Pressure-Time (P-t) History	331	(1)
The Geothermal Gradient	331	(2)
The Deformational Setting	333	(1)
Closing Remarks	333	(2)
Additional Reading	333	(2)
PART D TECTONICS	335	(166)
Whole-Earth Structure and Plate Tectonics	336	(32)
Introduction	336	(1)
Studying Earth's Internal Layering	337	(1)
Seismically Defined Layers of the Earth	337	(5)
The Crust	342	(6)
Oceanic Crust	342	(1)
Continental Crust	342	(6)
The Moho	348	(1)
The Mantle	348	(2)
Internal Structure of the Mantle	348	(2)
Mantle Plumes	350	(1)
The Core	350	(1)
Defining Earth Layers Based on Rheologic Behavior	350	(5)
The Lithosphere	351	(2)
The Asthenosphere	353	(1)
Isostasy	353	(2)
The Tenets of Plate Tectonics Theory	355	(4)
Basic Plate Kinematics	359	(5)
Absolute Plate Velocity	359	(1)
Relative Plate Velocity	360	(1)
Using Vectors to Describe Relative Plate Velocity	361	(3)
Triple Junctions	364	(1)
Plate-Driving Forces	364	(2)
The Supercontinent Cycle	366	(1)
Closing Remarks	367	(1)
Additional Reading	367	(1)
Geophysical Imaging of the Continental Lithosphere	368	(14)
Frederick A. Cook
Introduction	368	(1)
What is Seismic Imaging?	368	(2)
How are Data Interpreted?	370	(1)
Some Examples	370	(2)
The Crust---Mantle Transition	372	(2)
The Importance of Regional Profiles---Longer, Deeper, More Detailed	374	(1)
An Example from Northwestern Canada	375	(4)
Other Geophysical Techniques	379	(2)
Closing Remarks	381	(1)
Additional Reading	381	(1)
Rifting, Seafloor Spreading, and Extensional Tectonics	382	(30)
Introduction	382	(3)
Cross-Sectional Structure of a Rift	385	(5)
Normal Fault Systems	385	(4)
Pure-Shear versus Simple-Shear Models of Rifting	389	(1)
Examples of Rift Structure in Cross Section	389	(1)
Cordilleran Metamorphic Core Complexes	390	(4)
Formation of a Rift System	394	(2)
Controls on Rift Orientation	396	(1)
Rocks and Topographic Features of Rifts	397	(5)
Sedimentary-Rock Assemblages in Rifts	397	(1)
Igneous-Rock Assemblage of Rifts	397	(2)
Active Rift Topography and Rift-Margin Uplifts	399	(3)
Tectonics of Midocean Ridges	402	(3)
Passive Margins	405	(3)
Causes of Rifting	408	(2)
Closing Remarks	410	(2)
Additional Reading	410	(2)
Convergence and Collision	412	(32)
Introduction	412	(2)
Convergent Plate Margins	414	(15)
The Downgoing Slab	415	(3)
The Trench	418	(2)
The Accretionary Prism	420	(4)
The Forearc Basin and the Volcanic Arc	424	(1)
The Backarc Region	425	(3)
Curvature of Island Arcs	428	(1)
Coupled versus Uncoupled Convergent Margins	428	(1)
Basic Stages of Collisional Tectonics	429	(7)
Stage 1: Precollision and Initial Interaction	431	(2)
Stage 2: Abortive Subduction and Suturing	433	(2)
Stage 3: Crustal Thickening and Extensional Collapse	435	(1)
Other Consequences of Collisional Tectonics	436	(6)
Regional Strike-Slip Faulting and Lateral Escape	436	(2)
Plateau Uplift	438	(1)
Continental Interior Fault-and-Fold Zones	438	(2)
Crustal Accretion (Accetionary Tectonics)	440	(2)
Deep Structure of Collisional Orogens	442	(1)
Insights from Modeling Studies	442	(1)
Closing Remarks	443	(1)
Additional Reading	443	(1)
Fold-Thrust Belts	444	(32)
Stephen Marshak
M. Scott Wilkerson
Introduction	444	(4)
Fold-Thrust Belts in a Regional Context	448	(4)
Tectonic Settings of Fold-Thrust Belts	448	(4)
Mechanical Stratigraphy	452	(1)
Geometry of Thrusts and Thrust Systems	452	(7)
A Cross-Sectional Image of a Thrust Fault	452	(3)
Thrust Systems	455	(2)
Overall Fold-Thrust Belt Architecture	457	(2)
Thrust-Related Folding	459	(6)
Mesoscopic- and Microscopic-Scale Strain in Thrust Sheets	465	(1)
Fold-Thrust Belts in Map View	465	(3)
Balanced Cross Sections	468	(2)
Mechanics of Fold-Thrust Belts	470	(4)
Closing Remarks	474	(2)
Additional Reading	474	(2)
Strike-Slip Tectonics	476	(25)
Introduction	476	(3)
Transform versus Transcurrent Faults	479	(3)
Transform Faults	479	(2)
Transcurrent Faults	481	(1)
Structural Features of Major Continental Strike-Slip Faults	482	(11)
Description of Distributed Deformation in Strike-Slip Zones	482	(2)
The Causes of Structural Complexity in Strike-Slip Zones	484	(3)
Map-View Block Rotation in Strike-Slip Zones	487	(1)
Transpression and Transtension	487	(3)
Restraining and Releasing Bends	490	(2)
Strike-Slip Duplexes	492	(1)
Deep-Crustal Strike-Slip Fault Geometry	492	(1)
Tectonic Setting of Continental Strike-Slip Faults	493	(4)
Oblique Convergence and Collision	493	(1)
Strike-Slip Faulting in Fold-Thrust Belts	493	(1)
Strike-Slip Faulting in Rifts	493	(2)
Continental Transform Faults	495	(2)
Oceanic Transforms and Fracture Zones	497	(1)
Closing Remarks	498	(3)
Additional Reading	498	(3)
PART E REGIONAL PERSPECTIVES	501	(127)
A Global View	502	(7)
Introduction	502	(1)
Global Deformation Patterns	503	(1)
What Can We Learn from Regional Perspectives?	504	(2)
Some Speculation on Contrasting Orogenic Styles	506	(1)
Closing Remarks and Outline	507	(2)
Additional Reading	508	(1)
Eastern Hemisphere	509	(47)
The Tectonic Evolution of the European Alps and Forelands	510	(15)
Stefan M. Schmid
Introduction	510	(1)
The Major Tectonic Units of the European Alps	510	(2)
The Major Paleogeographic Units of the Alps	512	(2)
Three Alpine Transects and Their Deep Structure	514	(3)
Inferences Concerning Rheologic Behavior	517	(1)
Evolution of the Alpine System and Its Forelands in Time Slices	517	(5)
Recent Movements in the Upper Rhine Graben	522	(1)
Closing Remarks	523	(1)
Additional Reading	524	(1)
The Tibetan Plateau and Surrounding Regions	525	(10)
Leigh H. Royden
B. Clark Burchfiel
Introduction	525	(1)
Precollisional History	525	(2)
Postcollisional Convergent Deformation	527	(3)
Crustal Shortening and Strike-Slip Faulting	530	(2)
Extension of the Tibetan Plateau	532	(1)
Closing Remarks	533	(1)
Additional Reading	533	(2)
Tectonics of the Altaids: An Example of a Turkic-type Orogen	535	(12)
A. M. Celal Sengor
Boris A. Natal'in
Introduction	535	(3)
The Present Structure of the Altaids	538	(1)
Evolution of the Altaids	539	(6)
Implications for Continental Growth	545	(1)
Closing Remarks	545	(1)
Additional Reading	545	(2)
The Tasman Orogenic Belt, Eastern Australia: An Example of Paleozoic Tectonic Accretion	547	(9)
David R. Gray
David A. Foster
Introduction	547	(1)
Crustal Structure and Main Tectonic Elements	548	(3)
Timing of Deformation and Regional Events	551	(3)
Mechanics of Deformation in Accretionary Orogens	554	(1)
Additional Reading	555	(1)
Western Hemisphere	556	(72)
The North American Cordillera	557	(9)
Elizabeth L. Miller
Introduction	557	(1)
Precambrian and Paleozoic History	558	(1)
Mesozoic History	559	(1)
Cenozoic History	560	(4)
Closing Remarks	564	(1)
Additional Reading	565	(1)
The Cascadia Subduction Wedge: The Role of Accretion, Uplift, and Erosion	566	(9)
Mark T. Brandon
Introduction	566	(1)
Accretionary Flux	566	(1)
Wedges, Taper, and Stability	567	(1)
Double-Sided Wedges	567	(1)
Subduction Polarity and Pro-Side Accretion	568	(1)
The Cascadia Subduction Zone	569	(5)
Comparison between the Cascadia and Alpine Wedges	574	(1)
Additional Reading	574	(1)
The Central Andes: A Natural Laboratory for Noncollisional Mountain Building	575	(7)
Richard W. Allmendinger
Teresa E. Jordan
Introduction	575	(1)
The Andean Orogeny	575	(2)
Late Cenozoic Tectonics of the Andes	577	(3)
Crustal Thickening and Lithospheric Thinning	580	(1)
Closing Remarks	581	(1)
Additional Reading	581	(1)
The Appalachian Orogen	582	(11)
James P. Hibbard
Introduction	582	(1)
Overview	582	(1)
Tectonic Components	583	(4)
Assembly	587	(4)
Closing Remarks	591	(1)
Additional Reading	591	(2)
The Caledonides	593	(14)
Kevin T. Pickering
Alan G. Smith
Introduction	593	(4)
Late Precambrian---Cambrian Extension and Passive Margins	597	(1)
Late Precambrian---Cambrian Arcs, Northern and Northwestern Gondwana	597	(1)
Early-Middle Ordovician Arcs, Marginal Basins, and Ophiolites	598	(1)
Early Ordovician Breakup of the Northwest Margin of Gondwana	599	(1)
Middle-Late Ordovician Subduction, Continental Fragmentation, and Collisions	600	(1)
Middle Ordovician---Silurian Closure of the Eastern Iapetus Ocean	601	(2)
Late Ordovician Icehouse	603	(1)
Ordovician-Silurian Magmatic Arcs Elsewhere in Europe	604	(1)
Postorogenic Continental Sedimentation and Igneous Activity	605	(1)
Closing Remarks	605	(1)
Additional Reading	606	(1)
Tectonic Genealogy of North America	607	(8)
Paul F. Hoffman
Introduction	607	(1)
Phanerozoic (545-0 Ma) Orogens and Pangea	608	(1)
Neoproterozoic (1000-545 Ma) Orogens and Gondwanaland	608	(1)
Mesoproterozoic (1600-1000 Ma) Orogens and Rodinia	609	(1)
Paleoproterozoic (2500-1600 Ma) Collisional Orogens and Nuna	610	(1)
Paleoproterozoic Accretionary Orogens Add to Nuna	611	(1)
Archean Cratons and Kenorland	612	(1)
Closing Remarks	613	(1)
Additional Reading	613	(2)
Phanerozoic Tectonics of the United States Midcontinent	615	(13)
Introduction	615	(1)
Classes of Structures in the Midcontinent	616	(7)
Some Causes of Epeirogeny	623	(2)
Speculations on Midcontinent Fault-and-Fold Zones	625	(1)
Closing Remarks	626	(1)
Additional Reading	627	(1)
Appendix 1 Spherical Projections	628	(3)
Appendix 2 Geologic Timescale	631	(2)
Credits	633	(8)
Index	641