Transcript GEOLOGIC MAPPING 2014 EVENT OVERVIEW PRESENTED BY: MARK A. VANHECKE NATIONAL SCIENCE OLYMPIAD EARTH-SPACE SCIENCE EVENT CHAIR [email protected].

GEOLOGIC MAPPING
2014 EVENT OVERVIEW
PRESENTED BY:
MARK A. VANHECKE
NATIONAL SCIENCE OLYMPIAD
EARTH-SPACE SCIENCE EVENT CHAIR
[email protected]
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
GEOLOGY AND GEOLOGIC HISTORY
PRACTICAL APPLICATIONS
NATURAL RESOURCES
GEOHAZARDS
GROUNDWATER
2014 GEOLOGIC MAPPING
BASIC FEATURES
OF GEOLOGIC MAPS
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
STRATIGRAPHIC COLUMNS
CROSS SECTIONS
BLOCK DIAGRAMS
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
SW
In a strike-dip symbol, the larger line refers to the
Strike
DRAWING A GEOLOGIC CROSS SECTION
Dip refers to the angle between a horizontal
plane and the inclined stratum of rock, fault or
fracture
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
WORKSHEET 1: SECTION 1 ANSWERS
East
Strike
East
Dip
40
40
35
West
35
SE
40
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
43
Dip= 43ºN
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
WORKSHEET 1: SECTION 2 ANSWERS
38
52
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
INTERPRETING
A 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
INTERPRETING A BLOCK DIAGRAM
OLDEST
YOUNGEST
INTERPRETING A BLOCK DIAGRAM
Disconformity
Original Horizontality
Superposition
Angular Disconformity
Igneous Intrusions
Nonconformity
Faults
INTERPRETING A BLOCK DIAGRAM
INTERPRETING A BLOCK DIAGRAM
OLDEST
YOUNGEST
2014 GEOLOGIC MAPPING
RESOURCES
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.
http://www.wwnorton.com/college/geo/geolab/animations.
aspx
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
http://www.youtube.com/watch?v=ZZHgxlh0PQ4
Excellent Video Series I used for the Block Diagram
Activities (three parts to series)
http://www.youtube.com/watch?v=Vgo8Z63n60g
Excellent description of drawing a Cross Section I used
for this activity