A perfect presentation of mountain building, fold and faults.

1. Deformation and .
Mountain Building
A. Plate Tectonics and
Stress
B. Rock Deformation
C. Geologic Structures
D. Origin of Mountains
E. Continental Crust

2. Tectonic Stresses  Large Scale Strain
of the Crust i.e., Geologic Structures
 Inner core: Solid iron
 Outer core: Liquid iron,
convecting (magnetic field)
 Mantle (Asthenosphere) :
Solid iron-magnesium
silicate, plastic, convecting
 Crust (Lithosphere): Rigid,
thin
5-30km
Crust:
Rigid,
Thin
Mantle:
Plastic,
Convecting

3. Tectonics and
Structural Geology
Tectonic Stresses
resulting from
Internal Energy
(heat driving convection)
Strains (deforms) the Mantle
and Crust
Bends Rocks, i.e.,
ductile strain (Folds)
Breaks Rock, i.e.,
brittle strain (Joints) and
Moves large blocks along
Faults and
Releases energy 
Earthquakes

4. Fig. 10-CO, p. 216

5. Folds and Faults (Palmdale, Ca)
See Fig. 10-2a, p. 219

6. Eastern Pennsylvania
Northwestern
Africa

7. Stresses
at Plate
Boundaries
 Divergent
(Tensional)
|
 Convergent
(Compressional)
|
 Transform
(Shear)
e.g., Pacific NW

8. GeoloGic
StructureS
 Different stresses result in
various forms of strain
(geologic structures)
 Folds (compressive
stresses may cause ductile
strain)
 Faults (Any type of stress
may cause brittle strain.
The type of fault depends
on the type of stress)

9. StikeS and dipS are uSed to
identify GeoloGic
StructureS

10. Strike and dip
 Define and map the orientation of
planar features
 Bedding planes (sedimentary rocks)
 Foliation
 Joints
 Faults
 Dikes
 Sills
 Ore Veins
Fig. 10-4, p. 221

11. Strike and
dip
 Strike: The line of
intersection between
the plane and a
horizontal surface
 Dip: Angle that the
plane makes with
that horizontal plane
Fig. 10-4, p. 221
Strike and Dip
Map Symbol

12. SippinG BeddinG planeS
 Youngest (top)
 P: Permian
 P: Pennsylvanian
 M: Mississippian
 D: Devonian
 S: Silurian
 O: Ordovician
 C: Cambrian
 Oldest (bottom)
D
S
O
Sedimentary Rocks Dip in the
direction of younger rocks

13. Deciphering the geology
of ohio
Using Dipping BeDDing planes
 Beds Dip 2o
, West
 Younger rocks,
West
 Mirror image east of
Sandusky?
Sandstone Shale Limestone
M O D
2o2o2o

14. anticline (folD)

15. anticline (folD)

16. syncline (folD)

18. plUnging
anticline

19. folD terminology
 Axis
 Axial Plane
 Plunging
 Age of rocks
and
outcrops
Axis Axis

20. plUnging anticline,
coloraDo

21. eastern pennsylvania
 Folds and faults resulting from
compressive stresses
 Anticlines (many plunging)
 Synclines (many plunging)
 Reverse faults
 Thrust faults

22. Domes anD Basins

24. BeDrock
geology of the
michigan Basin
 During and after the
deposition of
Michigan’s
sedimentary rocks
 The crust warped
downward
 Exposing younger
rocks in the center
and
 Older rocks on the
rim (e.g. Toledo)

25.  When shallow crust is strained
rocks tend to exhibit brittle strain
Brittle Strain  JointS

26. Sheet JointS

27. Defining fault
orientation
 Strike of fault plane
parallels the
 fault trace and
 fault scarp
 Direction of Dip of
the fault plane
indicates the
Hanging wall block
Fig. 10-11a, p. 227

28. fault:
 Movement
occurring
along a
discontinuity
 Brittle strain
and
subsequent
movement as
a result of
stress
 Fault
terminology

29. fault
S
 Fault: When
movement
occurs along
a discontinuity
 Fault type
depends on
the type of
stress

30. normal faultS

31. normal faultS, horStS anD
graBenS

32. StructureS at Divergent
BounDarieS
 Tensional Stresses cause brittle strain and
formation of sets of normal faults
 i.e., Horsts and Grabens

33. horStS anD graBenS
 Older Rocks are exposed along the ridges
formed by the horsts
 Younger rocks lie beneath the grabens
 Sediment fills in the linear valleys
Horst
Graben
Horst
Graben

34. nevaDa
 “Washboard
topography” is the result
of Horsts and Grabens
 A.k.a, Basin and Range
 E.g., Humbolt Range
 E.g., Death Valley
(Graben)

35. horSt anD graBen,
nevaDa
Humboldt Range, Northern Nevada Fig. 10-15b, p. 233
Graben
Horst

36. horSt anD graBen,
nevaDa
Humboldt Range, Northern Nevada
Graben
Horst

37. ReveRse and ThRusT
FaulTs
 Compressive stress
causes the hanging
wall to move upward
relative to the foot wall
 Reverse Fault
 At convergent plate
boundaries ancient
rocks can be thrust
over younger rocks
 Thrust Fault

38. sTRucTuRes aT a Passive
conTinenTal MaRgin
 Resulting from continental breakup
 E.g., The Americas and Africa

39. salT doMes: e.g., Texas
 Rising of less dense
salt
 Stretches overlying
crust
 Forming normal
faults and
 Oil traps

40. sTRucTuRal oil TRaPs

41. ThRusT FaulT: glacieR nP,
MonTana
Old
Younger

42. sTRucTuRes aT a
conveRgenT BoundaRy

43. Structures within Mountain Belts

44. Compressional and Tensional
Structures

45. e.g., The aPls
 Intense folding and thrusting of
sedimentary rocks

46. sTRike sliP FaulTs
 Physiographic
Features

47. san andReas
FaulT
 What type of fault is this?
 What other features are
associated with the fault?

48. san andReas FaulT