1. GEOLOGIC MAPPING
2014 EVENT OVERVIEW

2. PRESENTED BY:
Mark a. vanhecke National Science Olympiad Earth-space science event chair

3. PRESENTATION OBJECTIVES:
Identify event parameters for the 2014 Geologic Mapping Event
Identify the basic features of geologic maps
Use a geologic map diagram to construct a cross section and project map features
Interpret a block diagram and order rock strata from oldest to youngest

4. 2014 GEOLOGIC MAPPING
EVENT OVERVIEW

5. 2014 EVENT OVERVIEW Identify basic features of geologic maps
Interpret geologic map features including intrusions, subsurface geometries, deformation features and subsurface depositional features
Identify folds, fault types and erosional patterns
Construct fault sections, topographic profiles, projections of mapped features

6. 2014 EVENT OVERVIEW
Identify structural elements shown in geologic maps including synforms, antiforms, basins, monoclines, domes and saddles
Determine bed thicknesses, true dip and orientations of planes from point

7. 2014 GEOLOGIC MAPPING
WHAT IS A GEOLOGIC MAP?

8. WHAT ARE GEOLOGIC MAPS? A geologic map shows: Mappable Rock Layers
Mappable sediment layers that cover up the rocks
Geologic structures including folds, faults and intrusions
‘Mappable’ rock layers are recognized consistently across a landscape

9. WHAT ARE GEOLOGIC MAPS?
Mappable units of rock and sediment may be identified using letter symbols

10. WHAT ARE GEOLOGIC MAPS?
Mappable units of rock and sediment may also use colors, patterns or combinations of letter symbols and colors/patterns

11. Geology and geologic history

12. Practical applications

13. Natural resources

14. geohazards

15. Groundwater

16. BASIC FEATURES OF GEOLOGIC MAPS
2014 GEOLOGIC MAPPING
BASIC FEATURES OF GEOLOGIC MAPS

17. A geologic map shows the kinds of rock layers that you would find in a certain place

18. BASIC FEATURES OF GEOLOGIC MAPS
The basic features of a geologic map are the map itself and the legend or key used to explain the symbols, colors/patterns

19. Stratigraphic columns
A geologic map shows the kinds of rock layers that you would find in a certain place
Stratigraphic columns

20. A geologic map shows the kinds of rock layers that you would find in a certain place
Cross sections

21. A geologic map shows the kinds of rock layers that you would find in a certain place
Block diagrams

22. DRAWING A CROSS SECTION
2014 GEOLOGIC MAPPING
DRAWING A CROSS SECTION

23. DRAWING A GEOLOGIC CROSS SECTION
A geologic map identifies different rock types and where they can be seen on the surface

24. DRAWING A GEOLOGIC CROSS SECTION
A cross section of a geologic map is a vertical slice of the Earth’s surface that shows what the underlying geologic structure at that location looks like

25. DRAWING A GEOLOGIC CROSS SECTION
A cross section of a geologic map also shows the boundaries between different types of rock found on the surface

26. DRAWING A GEOLOGIC CROSS SECTION
A cross section of a geologic map also shows the orientation of rock layers where they intersect the surface.
The orientation or direction of rock layers is expressed as Strike and Dip.

27. DRAWING A GEOLOGIC CROSS SECTION
Strike refers to the compass bearing (direction) of a line formed by the intersection of a horizontal plane and an inclined layer of rock. N NE SW
Angle of the strike is from NE to SW
In a strike-dip symbol, the larger line refers to the Strike

28. DRAWING A GEOLOGIC CROSS SECTION
Dip refers to the angle between a horizontal plane and the inclined stratum of rock, fault or fracture
45º
Horizontal Plane
Strike Line
Dip Direction

29. DRAWING A GEOLOGIC CROSS SECTION
In a strike-dip symbol, the smaller line indicates Dip 45

30. DRAWING A GEOLOGIC CROSS SECTION
The location of the dip line in relation to the strike line indicates the direction of the dip. 24
Rock layer dips to the west 45
Rock layer dips to the east

31. DRAWING A GEOLOGIC CROSS SECTION
Solve the strike and dip problems given on Worksheet 1 Section 1

32. WORKSHEET 1: SECTION 1 ANSWERS
East
Strike
East 40 35 50 40
Dip
West 40 35 50 SE SE NW

33. DRAWING A GEOLOGIC CROSS SECTION
Strike and Dip is usually expressed in bearings (Quadrants)

34. DRAWING A GEOLOGIC CROSS SECTION
Writing strike and dip coordinates
Strike= N45ºW 24
Dip= 24ºSW
Dip= 43ºN 43
Strike= N90ºE

35. DRAWING A GEOLOGIC CROSS SECTION
On Worksheet 1 Section 2 measure the angle of strike and write out the bearings for the strike and dip measurements given

36. WORKSHEET 1: SECTION 2 ANSWERS52 38
Strike = N44ºW (or S44ºE)
Dip= 52ºSW
Strike= N82ºE (or S82ºW)
Dip= 38ºNW

37. DRAWING A GEOLOGIC CROSS SECTION
STEP 1
On Worksheet 2, draw a horizontal line just below the diagram as shown below

38. DRAWING A GEOLOGIC CROSS SECTION
STEP 2
Transfer all available information from the diagram as shown to the line you just drew.

39. DRAWING A GEOLOGIC CROSS SECTION
STEP 3
Indicate the locations of boundaries between layers on the horizontal line as shown

40. DRAWING A GEOLOGIC CROSS SECTION
STEP 4
Use a protractor to measure the direction and angle of the dip and draw a small line on the horizontal line for each as shown

41. DRAWING A GEOLOGIC CROSS SECTION
How are different outcrops of the same layer connected?
How do dip angles and directions change above and below the surface?

42. DRAWING A GEOLOGIC CROSS SECTION
STEP 5
Connect the boundary lines for each layer as shown

43. PRINCIPLES OF STRATIGRAPHY
2014 GEOLOGIC MAPPING
PRINCIPLES OF STRATIGRAPHY

45. INTERPRETING A BLOCK DIAGRAM
2014 GEOLOGIC MAPPING
INTERPRETING A BLOCK DIAGRAM

46. INTERPRETING A BLOCK DIAGRAM
Block diagrams show different rock strata and changes that have been made over time to their layering

47. INTERPRETING A BLOCK DIAGRAM
Original Horizontality
Superposition
Fault
Nonconformity
Igneous Intrusion

48. INTERPRETING A BLOCK DIAGRAM

49. INTERPRETING A BLOCK DIAGRAM
OLDEST
YOUNGEST

50. INTERPRETING A BLOCK DIAGRAM
Disconformity
Original Horizontality
Superposition
Angular Disconformity
Igneous Intrusions
Faults
Nonconformity

51. INTERPRETING A BLOCK DIAGRAM

52. INTERPRETING A BLOCK DIAGRAM
OLDEST
YOUNGEST

53. 2014 GEOLOGIC MAPPING
RESOURCES

54. RESOURCES http://geomaps.wr.usgs.gov/parks/gmap/gmap3.html
USGS Geologic Maps. An excellent discussion of strike and dip. It also provides a good introduction to map keys.
This web-based Norton Publishing Lab Manual for Introductory Geology is filled with animations that show the movements of geologic features that are identified on many maps
Excellent Video Series I used for the Block Diagram Activities (three parts to series)
Excellent description of drawing a Cross Section I used for this activity