GIS In Archaeology

Lab Exercise 2 – Introduction to ArcGIS II

Step 1: Load Exercise Data
Verify that all data have been copied to a folder called GIS_In_Archaeology on your working drive. For this handout the folder has been created on the E-drive of the system computer.

Step 2: ArcCatalog Overview

Within ArcGIS the ArcMap program is our primary tool for bringing data sets together to create maps and analyze geographic data. There is another program called ArcCatalog which is created to help us manage geographic data sets.

Start ArcCatalog by clicking the Start menu, then choosing Programs, ArcGIS, then

The layout of ArcCatalog is similar to that of ArcMap in that the main window is divided into two panels. The purpose of the left panel is to list the data sources available for use, while the right panel is dedicated to viewing specific information about the data.

Step 3: Connect to GIS data folder

In order to be able to work with any geographic data we need to first tell ArcCatalog where the data is located. This is done in ArcCatalog by establishing a connection to the folder(s) where the data are stored.

A connection to data is establish by using the Connect To Folder tool from the main toolbar

Use the Connect to Folder window to select the E:\GIS_In_Archaeology folder

An entry to E:\GIS_In_Archaeology is now added to the left panel of ArcCatalog:

Expand the entry for E:\GIS_In_Archaeology\Data by clicking the next to the entry in the left panel:

Beneath this entry now highlight the Continents.shp entry in the left panel. Notice that the right hand window now shows a schematic image of the Continents data set. Also notice that in the right hand window there are listings for 3 panels (Contents, Preview, and Metadata) select each of these panels to see the different data which are displayed

Also now notice that when the Metadata Panel is selected there is also the option to select 3 more sub-panels (Description, Spatial, and Attributes). Select each of these to see the different information which is displayed

Step 4: Start ArcMap
Leave ArcCatalog running and begin a new session of ArcMap. You can start ArcMap either from the Windows Program menu as we did last time or you can start it from within ArcCatalog by using the Launch ArcMap tool from the main toolbar.

Once ArcMap starts open the Lab_01.mxd map document once again.

Step 5: Add layers to a map document
Currently the map document basically displays the states of Mexico and the United States. Let’s now add the major cities to this map. There are two basic ways to add new data to the map. The first method is done from within ArcMap by using the Add Data icon from the main toolbar.

Using this tool brings up the Add Data dialog box which lists the data sources that are available within ArcCatalog. From the Add Data dialog box select E:\GIS_In_Archaeology\Data, then Mexico, and finally the Cities.shp data set.

The major cities of Mexico are now added to the map document.

A second way to add data is directly from ArcCatalog. Resize and position the ArcMap and ArcCatalog windows so that you can see them side by side. Open up the entry for USA so that the listings for Cities appears. Left click the Cities.shp data set and holding down the mouse button drag it until your mouse is over the map window of ArcMap. Release the mouse button and the major cities of the United States are added to the map document.

Step 6: Exploring Layer Properties
Looking at the map document we see that there are now two entries in the table of contents for Cities. One of these layers contains the cities for the United States while the other one contains the cities for Mexico. It will be helpful to relabel these layers so that it is clear which layer contains the cities for each country. Turn the layers on and off so that you can identify which layer contains which data.

Within ArcMap the label of a layer in the table of contents is one of the properties of the layer. Right click on the entry for the US cities in the table of contents and choose Properties from the pop-up menu.

Selecting the Properties entry brings up the property window for the layer. Notice that the Layer Properties window contains 9 different panels (i.e. General, Source, Selection, etc.):


Click the various layer properties panels to see the types of properties associated with each panel. To relabel the layer select the General tab and change the entry of the Layer Name box from Cities to US Cities and click OK.

Repeat the process for the Mexico Cities layer and relabel it to Mexican Cities.

Step 7: Modify Point Symbology
Right click on US Cities in the Table of Contents and open the Attribute table. Scroll over to the right of the table until you see the field called STATUS. Scroll down the table and see that cities are classified as Provincial Capitals, National Capitals, and other.

Let’s modify the map so that Provincial and National capitals can easily be distinguished from non-capital cities. Close the attribute table. Then right click on US Cities and open up the Layer Properties window.

In the Layer properties window select the Symbology panel. In the left hand window of this panel click on Categories and then Unique values. In the drop down list under Value Field select the field STATUS. Then click the Add All Values button. The symbology panel should look like this:

Currently all 3 entries use a symbol dot style as their symbol. Double click on the dot symbol next to National and provincial capital to bring up the symbol selector window.

In the left hand panel scroll down and until you find the Star 3 symbol. After clicking on the Star 3 symbol notice that the Color changes to green and the Size is now 18.00. Click on the green Color swatch, when the color palette shows up select one of the red swatches. Then modify the size to be 14.00.

Click the OK button to return to the symbology panel and repeat the above process for the Provincial capital entry. The symbology panel should now look like this:

Click OK to return to the original map document. Capital cities should now stand out from other cities on the map

Repeat this process for Mexican cities as well.

Step 8: Modify Polygon Symbology
We can perform a similar process for polygon layers by color coding them differently based on the value in a field. Right click on States in the table of contents and open the attribute table. There is a field called POP_ADMIN that contains the population of each state. Close the attribute table.

Right click on States and bring up the Layer Properties window. Again switch to the symbology panel. In the left window select Quantities, then Graduated colors. For Value: pick the field POP_ADMIN. Click the drop down box next to Color Ramp: and pick the bitonal color ramp that has green at one end of the spectrum and red at the other with yellow in the middle. Finally select the drop down box next to Classes and select the value 9 to classify the data into 9 separate classes:

Click OK to return to the map. Notice that high population states are color coded in red while low population states are color coded green:


Notice that on the map many of the higher population states are also some of the larger states (ie. Texas, California, Michigan). We can modify the map to show population density if we divide each state’s population level by the area of the state. If you open the attribute table for States you will see that there are fields containing the area in square miles and square kilometers for each state.

Right click on States and open up the layer properties. Change to the Symbology panel and in the drop down list next to Normalization: select the field SQKM.

This process will “normalize” the population of each state by dividing the population by the area in square kilometers. Click OK to return to the map and notice how the pattern has changed.

Step 9: Perform a Geographic Selection

If we want to know how many cities fall within the boundaries of one of the states we can do that very simply by zooming in on the state and counting how many points fall within it’s boundaries. But many times there is much more data than we can manage by these manual techniques. However, since the GIS system contains both spatial and attribute information on the data we can use it’s powerful tools to help with this problem.

Add the Towns layer from the Mexico folder to your map. You will see that the whole of Mexico is literally covered with overlapping small points. Openin the attribute table for Towns indicates that there are 81174 mapped locations.

Suppose we want to find out how many towns are mapped within the boundaries of the Mexican state of Chihuahua. Obviously this would be an impossible task by hand, so we will let the GIS do this for us.

First let’s temporarily turn off the Towns layer so that we can see that states of Mexico better. Next open up the attribute table for the States layer and highlight the row for Chihuahua (notice that the entry is highlighted both in the table and the map)

Turn the Towns layer back on and then from the Selection menu pick the entry for Select by Location

In the Select By Location dialog box, select the checkbox next to Towns, then in the drop-down list select States under the label “the features in this layer.” The Select By Location window should look like this:

Reading through the dialog box the operation it will perform is “select the features from the layer Towns that intersect the selected features in the States layer.” Hit the apply button and then close and map will now have selected all the towns that fall inside the boundary of the state of Chihuahua (the state we selected from the States layer).

To find out how many towns fall within the boundary of Chihuahua, right click on the layer Towns in the table of contents and open it’s attribute table. Looking at the bottom line of the attribute table we see that 7712 of the 81174 records have been selected, so 7712 there are 7,712 points in the town layer that fall within the boundary of the state of Chihuahua.

Step 10: End Map Session
End the current map session. If you want to save the current map document, go to File -> Save As and save the map as Lab_02.mxd. Otherwise discard the changes when you exit ArcMap