Spring 2013
ArcGIS for Geoscientists
GEOL 596
Lab 3: Importing XY data
Making a point layer from Excel
One of the most common things you will want to do in ArcGIS is bring in point data that you’ve
collected, like sample locations, or downloaded, like earthquake locations. The steps that you
will walk through today are useful for bringing any point data for which you have latitude and
longitude coordinates into ArcGIS as a point layer. This will require some basic spreadsheet
work, which we’ll do in Excel.
As you’ve already seen, little mistakes can throw big wrenches into this process. Sometimes
totally invisible mistakes throw big wrenches into the process. Try not to get frustrated – just be
very systematic in your work.
This lab has several parts:

Formatting data you already have in Excel (p. 2)

Downloading data and formatting it in Excel (p. 4)

Adding XY data to ArcGIS (p. 8)

Adding symbology and display options (p. 11)

Properly displaying strike and dip data (p. 14)

Adding lineations to strike and dip symbols (p. 18)
This lab should give you the skills you need to get XY data into ArcMap from anywhere – really
useful for a variety of purposes.
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ArcGIS for Geoscientists
GEOL 596
Formatting data you already have in Excel
Most research in geology involves some sort of spatially distributed point data that you’ve
collected. Most geologic maps have some sort of structural information (strikes and dips on
bedding, etc.), and most geologists also have sample locations. I’m going to use these two types
of data as examples here – while the importing process is exactly the same, the techniques for
setting up the data in Excel and applying symbology are somewhat different for each one.
In order to import properly into ArcGIS, your spreadsheet must have:


A single column for latitude in decimal degrees (xx.xxxxx), where N latitudes are
positive and S latitudes are negative, and
A single column for longitude in decimal degrees (xxx.xxxxx), where E longitudes are
positive and W longitudes are negative.
You must also know which datum the latitude and longitude data are referenced to. If you
used a handheld GPS to collect the data yourself, you should be able to find that information on
the GPS. If you estimated the lat-long by hand from a map, the paper map should have the datum
printed on it. If you got the data from someone else, it’s possible they were responsible enough
to annotate the spreadsheet with the datum. If not, you need to find out. Most commonly, the
default datum for a handheld GPS unit is WGS 1984. (Remember, this is NOT a projection. It is
just the reference for the geographic coordinates.)
It is also possible to import point data that has projected coordinates, like meters from a UTM
projection. The main idea is that you need to know about your own data – are they projected or
not, what is the datum if not, what is the projection if so.
You can then have any number of columns in your spreadsheet for whatever you want. You can
also add columns once you bring it in to ArcGIS, but it is definitely easier to do so in Excel.
Think about adding columns for information that you might use to display or sort the data.
Depending on the state of your data, you may or may not need to go through all of these steps.
1. Open your spreadsheet in Excel.
2. Save a new copy by selecting “Save as…” and make a new folder within the folder that
contains your geodatabase and the DEMs folder. Call the new folder XY_data, and save
your spreadsheet as fieldarea_datatype.xlsx (where fieldarea and datatype are replaced by
the appropriate words).
3. Look at your latitude and longitude columns. Are they in decimal degrees? There should
be no symbols (like °) or letters (like N or S) in the column with the number. Do your
data look different? Do not despair! There are lots of things you can do in Excel with
formulas and text-to-columns to make this work.
a. Is there a letter in the column with the number, separated by a space? Insert a
column to the right. Select the column with the data in it. Go to Data  Text to
Columns… Select Delimited and use the space to delimit the column; the letter
will now be separated into the new column and you can delete it.
b. Is there a symbol in the column with the number without a space? Insert a column
to the right. Select the column with the data in it. Go to Data  Text to
Columns… Select Delimited and use the symbol(s) to delimit the columns; the
number might now be distributed among many columns (see below).
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c. Is the number in multiple columns? (e.g. degrees, minutes, seconds) Insert a
column to the right of all three. Use a formula to calculate the decimal degrees
from the degrees, minutes, seconds format. The formula is ((S/60) + M)/60) + D
4. For your spreadsheet to import correctly, the first row must be your column headers, with
no other information above it, and no other information in rows below all of the data.
Make sure that this is the case with your spreadsheet.
5. In addition, all of the column headers must be formatted according to strict rules:
a. No spaces (these are often hiding at the end of words in Excel, and you should
just check each header to make sure there are no hidden spaces). Underscores are
allowed.
b. No symbols, including ) ( < > , . : ; & % $ # * ^ etc. This rule means that you
cannot have a header that is something like Elevation (m), which has both a
space and two forbidden symbols. Elevation_m is OK.
c. Column headers must start with a letter.
d. Column headers must contain only letters, numbers, and underscores.
e. Column headers must not exceed 64 characters.
Check all of your headers to see that they follow these rules. In particular, make sure
that the columns that have your latitude and longitude data are clearly labeled as such.
6. You also want to make sure that the data itself is formatted correctly, beyond the lat-long
coordinates. In general, you want to keep a single value per column. For example, if you
have a spreadsheet with geochronology data, you might have age and error data. Rather
than having this in a single column, you want to put it into two columns.
Bad!
Age_error
12.31 +/- 1.21
Age_Ma
Good!
Error_Ma
12.31
1.21
Spend some time looking through all of your data and making sure you have it how you
want it. You don’t have to have all numeric columns.
7. Your Excel spreadsheet can have multiple worksheets. Even if it only has a single
worksheet, go ahead and give it a name – you will see why when we add the file to
ArcGIS. Do this by double-clicking on the tab at the bottom of the spreadsheet, which
has a default of Sheet1. The name will become highlighted, and you can type what you
want. If you have multiple sheets, name them all.
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ArcGIS for Geoscientists
GEOL 596
Downloading XY data and formatting it in Excel
Here are some places where you might find point data that you want to download:
 The Global Earthquake Search (http://earthquake.usgs.gov/earthquakes/eqarchives/epic/)
at the USGS is a great place to download earthquake locations, depths, and magnitudes.
Note that this is in beta form right now.
 NAVDAT (http://www.navdat.org/), the Western North American Volcanic and Intrusive
Rock Database, where you can download geochemical and geochronological data that has
been submitted by others.
 Something paleo
 Something geothermal
 Paleo mag
 More examples
Each of these has slightly different processes for downloading the data, but the process once you
have the data is exactly the same.
1. Launch a browser and go to http://earthquake.usgs.gov/.
2. Click on Earthquakes in the upper left navigation.
3. Click on
in the right-hand navigation.
4. Read the top paragraph on this page carefully. Imagine that you want to download all of
the earthquakes in your field area, as far back in time as you can go. Fill in the search
parameters accordingly.
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5. Once you are successful, you will get a return on the page that looks something like this:
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Click on CSV. This does not actually prompt a file download, but gives you something
like this instead:
Looks like a complete mess, right? Don’t worry.
6. Select everything on the page, and copy it (right-click and select Copy, or use the menu
or keyboard shortcut).
7. Go to Excel and open a new workbook.
8. Right-click in the upper-left-most cell (A1) and select Paste. This pastes all of the data
into different rows, but all in the same column.
9. With all of the data still selected (just the first column appears selected), go to Data 
Text to Columns… and you should see this window:
If you are not already familiar with this process, you will be. It will become your friend.
10. The data you have copied and pasted is in CSV, or comma-separated values, format. That
means it is “delimited” (data in different columns is separated by commas) rather than
“fixed width” (which has an equal number of spaces per column). So keep the default
selection of delimited and click Next.
11. Select the appropriate delimiter in the next screen (comma) and deselect the others. You
should see the data separate into columns. Scroll through to see if it all looks OK.
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12. The final screen in the wizard offers you the opportunity to determine the format of each
column. I tend to leave these all as “General” and just click right to Finish, here, because
otherwise it can sometimes introduce errors into perfectly good data.
So you can just click Finish.
13. Hooray! This is starting to look better, but there is still a lot of clean-up to do in order to
bring it in to ArcGIS. Save your work in your XY_data folder, with a name something
like fieldarea_EQs.xlsx
14. Name the worksheet Fieldarea_EQs_all_data, and add a second worksheet (you can
either click on the plus sign in the tab next to the first worksheet or select Insert  Sheet
 Blank Worksheet). Name the second worksheet Fieldarea_EQs_edited.
15. Take a look at all of the data. What all do you really want to have at your fingertips in
ArcGIS? You know you want Latitude, Longitude, Depth, Magnitude. Do you care about
anything else? Probably not. Copy and paste just the columns you want from
EQs_all_data to EQs_edited. (Note: if you want to use the date and time information,
you’ll need to clean it up to make it useful. You can do this by being clever with the textto-columns process described above, but I won’t go through it now.)
16. Save your work.
17. Now go through the process described above for formatting your own data correctly.
Check the headers and scroll through to make sure things look OK.
Now we can bring in both your data and the data you downloaded into ArcGIS.
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Spring 2013
ArcGIS for Geoscientists
GEOL 596
Adding XY data to ArcGIS
There are a few different ways to bring your spreadsheet into ArcGIS. We’ll go through one of
them here, and you can then find the other ways in the Help document if you need them. The
principles are the same in all cases, so you should have no trouble.
1. Launch ArcMap. If you saved the map you made with the DEM and hillshade, open that.
If not, add them and make the colors and shading look the way you want them. Go ahead
and save this if you haven’t already.
2. The process for bringing in new data from an Excel file is a little different from adding a
raster image or a feature class. Go to File  Add Data  Add XY data…
3. This will open a new dialogue box for you to fill in.
Click on the file folder and navigate to your Excel
spreadsheet. You will see that the spreadsheet has a symbol like this:
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This is NOT what you want to add. You want to double-click on this, and you will be
able to see the individual worksheets within the workbook, which will have symbols like
this:
. This is why you want to rename your worksheets with meaningful names.
Select the sheet you want to add, and click Add.
4. Most likely, some of the drop-down boxes will auto-populate, perhaps even with the right
information! But you might need to modify them.
The fields correspond with the column headers you cleaned up. When you click on the
drop-down boxes, you should see all of your column headers. NOTE: If you don’t see all
of your headers, there is probably something wrong with your formatting, and you should
go back and edit the Excel file, checking for extra spaces and random symbols.
In the X field, you should select your Longitude column; in the Y field, select Latitude. If
you have elevation data in a column, you can select that in the Z field, but it’s not
necessary.
5. You also need to check the coordinate system. The program is probably just guessing, if
there is anything at all showing up in the description box. Read what is in the box, and
then click the Edit… button to find the right one.
6. This brings you to the familiar spatial reference window, where you select the correct
coordinate system. IMPORTANT: Here you are telling ArcGIS the coordinate system
that the data are currently in, NOT the one you want them to be in. So if your GPS data
are geographic, lat-long coordinates referenced to the WGS 84 datum, that is what you
would select here.
7. Once you’ve selected the coordinate system, it will show up in the description window,
and you can click OK.
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8. Most likely, the following warning will appear:
Read it. It’s important. Because we are going to export to a feature class so that you can
do the things you want to do, and because it makes your data more transferable. But for
now, you can note that you have been warned, and click OK.
9. Once you click OK, your points should show up on your map.

If they are not where you expected them to be, you probably chose the wrong
coordinate system.

If you can’t even find them, you can right click on the layer and select Zoom to
layer to see them – this is probably another indication that your coordinate system
is off.
10. In the Table of Contents, you will notice that your spreadsheet has the word “Events”
attached to it, so it looks like this:
This is related to that warning you got. Before you do any messing around with the
symbology and displays, you want to export this to a feature class so that the data live
within your geodatabase and can be manipulated and edited the same as all of the other
feature classes. So right-click on the layer and select Data  Export Data…
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11. You want to export your data to the feature dataset where all of the rest of your data lives:
The radio button may already be selected as the default – that’s fine. Then click on the
file folder to navigate to the feature dataset. You should get to a window where you can
see the continents file that we imported, along with the feature class you created. Change
the default name (Export_Output) to something more meaningful (e.g.,
fieldarea_samples). Click Save.
12. Click OK. You will be asked:
The answer is yes! You do.
13. The new layer will show up in the Table of contents. You can now delete the Events
layer, and work entirely with the new feature class you’ve created.
14. Save your work.
Congratulations! You’ve now successfully brought point data in to both your feature dataset
and your map.
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Spring 2013
ArcGIS for Geoscientists
GEOL 596
Adding symbology and display options
There are infinite ways to display and label point data using symbology options in ArcMap. This
will go through a few of the most common things you would do in a geologic map or figure.
1. To get started, add your earthquake XY data to the map you’ve created, following the
same steps as above.
2. Right-click on the layer and select Properties.
3. Click on the Symbology tab. The default symbology when you add a layer is
typically a simple symbol for every feature, so you are likely to see something like
this for your symbology window:
You can, of course, edit that symbol however you’d like by clicking on it, but the result is
that every feature in that feature class will be displayed using the same symbol. That’s not
terribly informative in the case of earthquake data, where you have not only location, but
depth and magnitude, which you can display. For example, let’s say you want to color the
symbols by depth and scale them by magnitude. You can do that! Let’s start with coloring
the earthquakes by depth.
4. Select Quantities in the left menu of the symbology tab.
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5. Select Graduated colors underneath Quantities. In other words, you want to base the
color of the symbol on a quantity in one of the fields, in this case, depth.
6. In the Value field, select Depth. This will automatically create some number of
categories, often five, and color them according to whatever color bar you have
selected. But you don’t need to go with the default – and you rarely want to.
7. Click on Classify, so that you can determine exactly how the breaks occur. The
default is to classify by natural breaks in the data, but you probably want to be a bit
more specific. You probably want to choose breaks manually according to more
meaningful depths in the earth. What you choose is going to depend on your data, so
the best way to figure this out is just to play around with it. You can change the
number of them and where they occur. When you are happy, click OK.
8. Back in the Symbology tab, select the color ramp you want to use to display the
quantities. You will want to choose something that is a continuous gradient and
creates different enough colors to be able to see them.
9. Now we want to make the symbols different sizes based on the magnitude of the
earthquake. Click on Advanced and select Size…
10. Here you should be able to select Magnitude as the factor that determines the size of
the symbol. Click OK, and OK again in the main window.
NOTE: I often find this result somewhat unsatisfying, and I do other things to make
this work better. One is to separate the earthquake data into two separate feature
classes, one that is earthquakes with a magnitude greater than 5.5, which is the
lowest end considered “significant”, and one for magnitudes less than 5.5. Then you
can color by depth and make the symbol size distinction more prominent.
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Spring 2013
ArcGIS for Geoscientists
GEOL 596
Properly displaying strike and dip data
If you are doing any geologic mapping, it is likely that you will have points that have associated
structural data, including strikes and dips. If you already have that data, here’s how to display the
symbols appropriately in ArcGIS. The final section of this lab will deal with best practices in the
field for collecting strike and dip data so that it is easily imported into ArcGIS.
1. If you already have a spreadsheet with strike and dip data, you want to follow
procedures as outlined above to make sure that you have latitude and longitude
coordinate data that is properly formatted to import this data into ArcGIS. You need
to have a column for strike that is in azimuth degrees, and a column for dip that uses
the right-hand rule. (Azimuth degrees means that N = 0, E = 90, S = 180, W = 270. It
is possible to convert, but best practice is to collect in azimuth to begin with.)
2. You also want to add a column, which I typically name Feature, in which you
describe in a word or two what you are measuring. The purpose of this column is to
take advantage of the symbology features in ArcGIS. You want to limit the number of
options that you fill in here to the number of different symbols you would use.
Typically, here are the options I would use:









Bedding
Horizontal bedding
Vertical bedding
Foliation
Fault
Dike
Slicks
Lineation
You might have some other feature, so add anything
you want to use a different symbol for.
3. Import the XY data, and export the data to make a new feature class.
4. Open the Properties dialogue box and navigate to the Symbology tab.
5. Select Categories  Unique Values in the left menu.
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6. In the Value Field, select the field you created called Feature.
7. Click Add All Values. This should populate the window with all of the possibilities
you typed into the spreadsheet, and a count of how many of those kinds of symbols
there are. Hopefully, you didn’t make too many typos, but it’s not a big deal if you
did – you can either correct it in the attribute table or just give the typos the same
symbols.
8. Right-click on bedding and select Properties for selected symbols… to get the
symbol selector window.
All of the appropriate geological symbols are already in ArcGIS, but you might have
to add them to what you are viewing. Scroll down initially to see what is there – if
you don’t see geology symbols, then click on Style References…
9. Scroll down and check the box next to Geology 24K (and anything else you want to
be able to use symbols for, but this is what you need right now). Click OK.
10. Back in the Symbol Selector window, scroll down until you see the geology symbols.
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Select the strike and dip symbol, which is called Inclined bedding – showing strike
and direction of dip.
Change the size of the symbol to 30, though you might need to mess around a bit to
get them to show at the right size.
11. Now click on Edit Symbol…
Unfortunately, Arc has this very annoying habit of not plotting the struke and dip
symbols directly on the points, so you need to fix this. Beneath the Preview window,
change the view to 400% so you can actually see this problem. Now use the offset X
and Y boxes to move the symbol so that the place where the dip tick intersects the
strike line is exactly on the center of the crosshairs. Click OK when you are done.
12. Click OK in the Symbol Selector dialogue.
When you get back to the Symbology tab, click Apply to apply your changes without
closing the window.
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13. Now you want to rotate the symbols according to their strike. So with Bedding still
selected in the symbol list window, click on Advanced and select Rotation…
14. You want to rotate your points by the value in the Strike field, and use Geographic
coordinates (where N = 0). Click OK, and Apply in the Symbology tab.
15. Now you want to label the symbols with the dip. Click on the Labels tab in the Layer
Properties window.
16. Select the check box to Label features in this layer. Click on the drop-down menu in
order to Define classes of features and label each class differently.
17. Click on Get symbol classes. This should populate the drop-down list with the same
list that you are selecting symbols for. Now you can select each item in the dropdown list and check/uncheck the checkbox indicating whether or not they will be
labeled. You will not, for example, label horizontal or vertical bedding with the dip,
since that is implied in the symbol you will use.
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18. In the Label Field, select Dip.
19. You will need to mess around with the size of the text and the placement properties in
order to get the labels to look the way that you want. This is most effectively done
through trial and error, to be honest. You can keep the window open and apply the
changes you make as many times as you want, however.
20. When you are happy with the labels so far, go back to the Symbology tab, right-click
on the other features, and select the appropriate symbol for horizontal bedding,
vertical bedding, fault planes, etc. You will go through the same process for all of
these symbols.
21. Be sure to save your work.
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Adding lineations to strike and dip symbols
If you have locations where you collected structural data that includes both planar and linear
features, there are some additional steps to getting those to display correctly. Once again, you
want to make sure your spreadsheet is formatted correctly to begin with. If you collected a
strike and dip of a metamorphic foliation and lineation at the same location, those two things
need two separate lines in your spreadsheet, even though the coordinates will be exactly the
same (in practice, this means I actually take two waypoints in the field for the two different
measurements). Assuming your spreadsheet is formatted correctly and you already have gone
through the section about properly displaying strike and dip symbols, here are the next steps.
1. In the Symbology tab, right-click on your lineation feature and select Properties for
selected symbols…
2. Choose the appropriate symbol for your lineation (probably the one called Lineation
– showing bearing and plunge).
3. Click on Edit symbol.
In the ultra tiny preview window, notice the location and orientation of the arrow.
Where the cross-hairs meet, that’s the location of your point. That preview is showing
you how the symbol will appear relative to the location of your point. Because this is
a lineation, you want the butt end of the arrow to be at your point, not the middle of
the arrow. You also want the default rotation of the arrow to be pointed straight up, or
north, so that you can rotate it by the trend.
4. Change the Angle so that the arrow points up.
5. Change the X and Y offset so that the butt end of the arrow is directly on the crosshairs. Click OK.
6. Then you want to use the same process to rotate the lineation symbol according to the
trend and label with the plunge.
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