Structural Geology 3443 Lab 1 Attitude

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Structural Geology (3443)Lab 1 Attitude
Location
Department of Geology University of Texas at
Arlington
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Lab 1 Attitude Location
Reference Frames Global Lat/Long UTM
Polar Local XYZ Polar
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Lab 1 Attitude Location
Attitude (Orientation of Planes) Strike - Bearing
of horizontal line Bearing Quadrant/Azimuth
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Lab 1 Attitude Location
Attitude (Orientation of Planes) Dip Vertical
angle measured in plane perpendicular to strike
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Lab 1 Attitude Location
Recording Strike Dip Estimate strike dip of
the map symbols below using the
following Quadrant Method Azimuth Method Right
Hand Convention
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Lab 1 Attitude Location
Dip and Dip Direction The dip direction is
always perpendicular to the strike. Convert your
previous strikes Dips to dip and dip direction
using the Quadrant Method and Azimuth Method
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Lab 1 Attitude Location
Attitudes of Lines (vectors) Lines are like dip
and dip direction except their attitude is called
Plunge q and Bearing b (or trend). The plunge
is measured in the vertical plane (like dip) The
bearing (or trend) is the horizontal angle to
that vertical plane.
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Lab 1 Attitude Location
Attitudes of Lines - Rake Lines common lie in
planes so their orientation can be described by
their Rake the acute angle between the line and
the strike of the plane measured in the plane. If
rake is measured need to specify the direction of
plunge of the line.
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Lab 1 Attitude Location
The Compass Used to measure the bearing of a line
or the strike of a plane The angle between
North and direction of the line or strike Used to
measure vertical angles and rakes.
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Lab 1 Attitude Location
The Compass see parts below
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Lab 1 Attitude Location
The Compass needle tries to line up with lines of
force of the Earths magnetic field, and those
lines of force point to Magnetic North (MN), and
only by chance do they ever point to the
rotational pole, or true North (TN).
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Lab 1 Attitude Location
The lines of force are nearly horizontal at the
equator but plunge steeper until they plunge 90
degrees and the magnetic poles. Compasses are
useless near the magnetic poles because the
needle is constrained to the horizontal plane.
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Lab 1 Attitude Location
The angular difference between the magnetic line
of force and true north is called the
DECLINATION, and varies from place to
place. Because the magnetic pole moves around,
maps showing declination must be updated every
year or so.
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Lab 1 Attitude Location
The angular difference between the magnetic line
of force and true north is called the
DECLINATION, and varies from place to
place. Because the magnetic pole moves around,
maps showing declination must be updated every
year or so.
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Lab 1 Attitude Location
Declination can be set on the compass so it reads
the angle between true North instead of to
magnetic North. The screw on the side of the
compass sets declination by moving the compass
card.
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Lab 1 Attitude Location
Using the Compass We will wait until the field
trip to learn how to measure strike Dip
Bearing and Plunge and make tape and compass
traverses. In the meantime do exercises 1, 2,
3, 5 7 at the end of Lab 1. Turn in next
Monday.