earth s architectural features folds, faults, fractures, joints, etc. structural geology study of these features

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3. 3 Oil / Gas Deposits Precious & Other Metal Deposits Hazards Analysis Earthquakes, Dams, Nuclear Plants, etc.

4. 4 Change in a rock mass Size Shape Orientation or Position

5. 5 Anywhere tectonic forces act upon formations e.g., Plate margins

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7. 7 Stress Confining Pressure (stress uniform in all directions) Differential Stress (nonuniform stress) Compressional Stress Tensional Stress Shear Stress

8. 8 Undeformed rocks

9. 9 Horizontal compression

10. 10 Horizontal tension

11. 11 Shearing

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13. 13 Deformation caused by stress - a strained body does not retain it’s original shape during/after deformation

14. 14 Deformation depends on Temperature & Confining Pressure Brittle & Ductile deformation Brittle – the material breaks Ductile – solid-state flow; change in size and shape without breakage

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16. 16 -Rock Type Rock Salt, Gypsum, Shale – flow ductilely Limestone, marble, schist - intermediate Granite, basalt – strong and brittle

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18. 18 Mapping Geological Structures Formations Strike and dip Folds Faults

19. 19 Formations Mappable rock unit Has definite upper & lower contacts (boundaries with other units) Obvious characteristics (i.e., rock type) which allows it to be traced from place to place Is different from other rock units Generally sedimentary rocks Named for nearby location/feature & main rock (or “Formation” if no single rock type)

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21. 21 Strike The compass direction of the line produced by the intersection of an inclined rock layer or fault, with a horizontal plane In northern hemisphere, measured from north Example: N75°E – the horizontal line is oriented 75º east of north

22. 22 Dip The angle of inclination of the surface of a rock unit or fault measured from a horizontal plane Dip direction – direction water would flow if you poured some on the surface

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24. 24 Wave-like undulations of strata Most form from compressional stresses Microscopic to Macroscopic in scale

25. 25 Limbs The two sides of a fold Axial Plane - The surface that divides a fold as symmetrically as possible Hinge The line drawn along maximum curvature Plunge - angle the hinge makes with the horizontal

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27. 27 Anticlines & Synclines Symmetrical & Antisymmetrical Overturned Recumbent (the axial plane is horizontal)

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29. 29 Monocline Rocks bent due to a fault in the underlying bedrock

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31. 31 Plunging folds

32. 32 Doubly-plunging folds Domes Large scale, circular or elongated upwarped folded sedimentary strata Basins Same, but downwarped

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36. 36 Faults are fractures in the crust along which appreciable displacement has taken place Sudden movement along faults are the cause of most earthquakes

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38. 38 Brevard Fault Zone (Chattahoochee) Towaliga Fault / Goat Rock Fault Pine Mountain, Warm Springs Cartersville Fault Rome Fault

39. 39 Dip-slip Faults Movement parallel to the dip of the fault surface Strike-slip Faults Movement parallel to the strike of the fault surface

40. 40 Hanging wall & footwall

41. 41 Normal Faults Reverse Faults Thrust Faults

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46. 46 Displacement is horizontal and parallel to the strike of the fault surface Right-lateral strike slip fault Left-lateral strike slip fault

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48. 48 Joints Fractures in rocks where no appreciable movement has occurred May have two or three intersecting sets Mineral deposits may be deposited within joints Joints may affect construction projects (highways, dams)

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