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Strikes and Dips (Geology Extension)   Michael Nerup Mar 28, 2002
Re: Strikes and Dips (Geology Extension)   Lucio D'Alberto Apr 12, 2002
Re: Strikes and Dips (Geology Extension)   Stephen Gardoll Apr 13, 2002
Re: Strikes and Dips (Geology Extension)   Michael Nerup Apr 15, 2002
Re: Strikes and Dips (Geology Extension)   Stephen Gardoll Apr 16, 2002
Re: Strikes and Dips (Geology Extension)   Matt McMackin Aug 24, 2004
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Subject Strikes and Dips (Geology Extension) 
Author Michael Nerup 
Date Mar 28, 2002 
Message Dear All,

I am looking for an extension which will plot strikes and dips (rakes and plunges)in Av 8.1.2. Does anyone have any suggestions?

Thanks.

cheers,
mikey
 
   
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Subject Re: Strikes and Dips (Geology Extension) 
Author Lucio D'Alberto 
Date Apr 12, 2002 
Message If you mean to rotate the symbols (for ArcMap):
TO ROTATE THE STRIKE / ATTITUDE SYMBOL BY THE AZIMUTH
- ArcView measure azimuth in counterclockwise way starting from “hour 3”, the compass generally measures clockwise from “hour 12”, this can be fixed using a formula to change the data.
- So first in your database/spreadsheet use the formula following these rules: a) if you have a strike or a lineation or an axis add 90 to your number and change it to a negative sign {plotstrike=-(strike+90)}; b) if you have the strike of dip just change it of sign {plotstrike=-(dipstrike); c) your final numbers must always be negative; d) do not keep in your spreadsheet columns with formulas because them are blank when you save as .dbf or .txt; e) the rules a,b,c) are correct for the attitude symbol that has the “dip line” toward “hour 12”, or for strike toward “hour 9” so be careful when choosing the symbol!
- When you have all your point in the shape file select the theme in the view, double-click on it and enter the legend editor; double click on the symbol and appear the “marker palette”
- Choose the appropriate symbol, then at base of LEGEND EDITOR go to ADVANCED and pick the FIELD (=column in database) that contain the azimuth data corrected to be plotted; then click OK, and then APPLY at the base of the LEGEND EDITOR

I sorted the data in 3 groups by the dip values: vertical attitudes (dip 90), horizontal atttitudes (dip 0 or HOR), and all the others (dip 1 to 89). In this way I have 3 classes to plot each with the appropriate symbol
 
   
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Subject Re: Strikes and Dips (Geology Extension) 
Author Stephen Gardoll 
Date Apr 13, 2002 
Message Basically, you just need to adjust the strike to handle the fact that ArcInfo rotates symbols using the Trigonomic reference frame. This system rotates symbols anticlockwise from the East (90degrees is North, 180degrees is West, 360degrees is East)

Another problem is the symbology. Not every symbol works the way you would like them too. Obviously, as you are geological-minded, you will understand the difference between, left hand rule, right hand rule, and dip azimuth. No one formula is perfect for each symbol. There are some exceptions in the geological symbols, the base location of the symbol, is not in the direction you want. There are also some symbols missing (darn!). I think dip-azimuth gives you the best option.

Convert the strike readings to dip azimuth, and thin flip the coordinate system and rotate for the 90 difference in the starting position of each system.

Good luck.

PS. I found sitting down with a stereo net and working out the equations for each quaderant the best. Then I just added a field and calculate the new (corrected for ArcMap) dip-direction.

 
  ------- Stephen J. Gardoll
------ Research Officer
----- Centre for Global Metallogeny
---- Department of Geology and Geophysics
--- University of Western Australia
-- 35 Stirling Highway Crawley WA Australia, 6009
- email: stephen@geol.uwa.edu.au 
   
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Subject Re: Strikes and Dips (Geology Extension) 
Author Michael Nerup 
Date Apr 15, 2002 
Message Dear Lucio and Stephen,

Thanks for your responses. I really appreciate them. I figured out how to do this after playing around in AV 8.1. I still can't figure out how to label the dips correctly. Labels are always on one side. Do either of you have a solution for this?

cheers,
mikey

P.S. Both answer my question. How do I split the award? 
   
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Subject Re: Strikes and Dips (Geology Extension) 
Author Stephen Gardoll 
Date Apr 16, 2002 
Message Select the dips by the quadrant of the strike. For example 0-90 first and position the text of the UPPER RIGHT. Then do 90-180 and position on the LOWER RIGHT and so on.

I usually end up positioning some of the dips manually. It doesn't take long.

Good luck. 
  ------- Stephen J. Gardoll
------ Research Officer
----- Centre for Global Metallogeny
---- Department of Geology and Geophysics
--- University of Western Australia
-- 35 Stirling Highway Crawley WA Australia, 6009
- email: stephen@geol.uwa.edu.au 
   
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Subject Re: Strikes and Dips (Geology Extension) 
Author Matt McMackin 
Date Aug 24, 2004 
Message Following your thread from April the strike and dip issue seems pretty clear but how do I get the geology extension?

Matt