GLG410/598--Computers in Earth and Space Exploration


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Lecture 18: Field exercise at Dreamy Draw, Phoenix Mtns.


On 9 November 2007 the GLG410 'Computers in Geology' class went to Dreamy Draw to see computers and other electronic equipment applied in a geologic investigation. The purpose of the trip was to make a detailed geolgic map of the area. Mapping was done on field-computers (tablets) as well as on paper/air photos. Furthermore, a total station was used to survey the topography of the mapped area. ArcMap was used to enter point observations (e.g., strike and dip of foliation) and geologic contacts. Due to typical Arizona weather (surplus of sunlight) using the field computers turned out to be rather challenging. Following below are the basemap (zipped) that was used and a combined shape file from the field trip.

The shape files (right-click and 'save target as'):

Generic version of digitized contacts and point observations
Generic "geologic" map of Dreamy Draw. A scanned paper map with pyramids for Arc already build.

The base map (right-click and 'save target as'):

Phoenix2004 partB (68139314.tif)
Phoenix2004 partC (75349028.tif)
Phoenix2004 minimum extent (20566312.tif)

Download these files, put them into a new folder and unzip them. When you open the *.mxd file in ArcMap you will most likely see many red exclamation points because the program cannot find the individual layers. Just go to the layer properties and set the data source.

How to get a Excel spread sheet (e.g. strike and dip measurements) into ArcMap

Assume you have measurements of strike and dip or any other spatially referenced (i.e. has geographic coordinates) data and want to import them into ArcMap to overlie them with other data. Following, we briefly show you how to get point observations from an Excel spread sheet (*.xls) into ArcMap. The following link contains some of the strike and dip values of foliation you have measured in the field. Please right-click and download the file.

Excel spreadsheat of strike and dip measurements



If you haven't opened the Dreamy Draw *.mxd file at this point please do so. You should see the following screen. To add the spread sheet, go to Tools => Add XY Data. Here you can browse to the *.xls file you downloaded (StrikeDipColl.xls). You will have to specify the x-field ( =Easting) and th y-field ( =Northing). You will also have to define the coordinate system. As you may rememeber all the GPS that we had in the field were on UTM Zone 12N, NAD 1983. That is the same coordinate system that the Dreamy Draw project is projected in. Thus, in the Add XY Data, under Coordinate System of Input Coordinates you can go to Edit.... Here you go to Import and select one of the shape files in your project (e.g. Contacts.shp).



Now you can pres OK and add the data. You will probably get an error message:



Read the instruction, press OK and follow it => Select and right-click the imported layer. Go to Data and press Export Data.



Make sure that, when asked what coordinate system to use, you select the data frame. Type in a name for the output file (which will be a shape file) and press ok.



When the new shape file is made you can add it (if not already done) and remove the raw data. The image below shows the position where strike and dip of foliation was measured.



Although knowing the position is nice, it would be more interesting to show the actual strike and dip direction. For that, go to the layer properties and then symbology. Under symbol you can go to more symbols and select the Geology 24k. Now, pick the proper sign. under advanced you can apply a rotation to the symbol.



Pick the Strike as the rotation angle and press ok.



Now you can see the orientation and dip direction of the foliation at each position. But you would probably also want to see the dip value. Go to the layer properties again and select label. Check the box that ask you whether you want to label features in this layer. Under String Text you define what label you want to put on the symbol. In our case we can to label with Dip. Press OK.







Very Nice!

Last modified: April 7, 2009