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GEOLOGIC MAPPING. 2014 EVENT OVERVIEW. mvanhecke@comcast.net. PRESENTED BY:. Mark a. vanhecke National Science Olympiad Earth-space science event chair. PRESENTATION OBJECTIVES:. Identify event parameters for the 2014 Geologic Mapping Event. Identify the basic features of geologic maps.
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GEOLOGIC MAPPING 2014 EVENT OVERVIEW
mvanhecke@comcast.net PRESENTED BY: Mark a. vanheckeNational Science OlympiadEarth-space science event chair
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
2014 GEOLOGIC MAPPING EVENT OVERVIEW
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
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
2014 GEOLOGIC MAPPING WHAT IS A GEOLOGIC MAP?
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
WHAT ARE GEOLOGIC MAPS? Mappable units of rock and sediment may be identified using letter symbols
WHAT ARE GEOLOGIC MAPS? Mappable units of rock and sediment may also use colors, patterns or combinations of letter symbols and colors/patterns
2014 GEOLOGIC MAPPING BASIC FEATURESOF GEOLOGIC MAPS
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
2014 GEOLOGIC MAPPING DRAWING A CROSS SECTION
DRAWING A GEOLOGIC CROSS SECTION A geologic map identifies different rock types and where they can be seen on the surface
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
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
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.
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 Angle of the strike is from NE to SW In a strike-dip symbol, the larger line refers to the Strike SW
DRAWING A GEOLOGIC CROSS SECTION Dip refers to the angle between a horizontal plane and the inclined stratum of rock, fault or fracture Strike Line Dip Direction Horizontal Plane 45º
DRAWING A GEOLOGIC CROSS SECTION In a strike-dip symbol, the smaller line indicates Dip 45
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
DRAWING A GEOLOGIC CROSS SECTION Solve the strike and dip problems given on Worksheet 1 Section 1
35 35 40 40 50 40 50 WORKSHEET 1: SECTION 1 ANSWERS East Strike East Dip West SE NW SE
DRAWING A GEOLOGIC CROSS SECTION Strike and Dip is usually expressed in bearings (Quadrants)
DRAWING A GEOLOGIC CROSS SECTION Writing strike and dip coordinates Strike= N45ºW 24 Dip= 24ºSW Dip= 43ºN 43 Strike= N90ºE
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
38 52 WORKSHEET 1: SECTION 2 ANSWERS Strike = N44ºW (or S44ºE) Dip= 52ºSW Strike= N82ºE (or S82ºW) Dip= 38ºNW
DRAWING A GEOLOGIC CROSS SECTION STEP 1 On Worksheet 2, draw a horizontal line just below the diagram as shown below
DRAWING A GEOLOGIC CROSS SECTION STEP 2 Transfer all available information from the diagram as shown to the line you just drew.
DRAWING A GEOLOGIC CROSS SECTION STEP 3 Indicate the locations of boundaries between layers on the horizontal line as shown
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
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?
DRAWING A GEOLOGIC CROSS SECTION STEP 5 Connect the boundary lines for each layer as shown
2014 GEOLOGIC MAPPING PRINCIPLES OF STRATIGRAPHY
2014 GEOLOGIC MAPPING INTERPRETINGA BLOCK DIAGRAM
INTERPRETING A BLOCK DIAGRAM Block diagrams show different rock strata and changes that have been made over time to their layering
INTERPRETING A BLOCK DIAGRAM Original Horizontality Superposition Fault Igneous Intrusion Nonconformity
INTERPRETING A BLOCK DIAGRAM OLDEST YOUNGEST
INTERPRETING A BLOCK DIAGRAM Disconformity Original Horizontality Superposition Angular Disconformity Igneous Intrusions Faults Nonconformity