 Mapping in QGIS, creating a core plethmap. You can create a core plethmap by changing the symbology to a graduated color scheme. In this example, we will be using census data to create a population density map. Right click on the layer and select properties. At the top, you will see a bar stating we are using a single symbol color scheme. Click on the dropdown arrow and select graduated. For value, select the dropdown arrow, scroll to the bottom, and click on the field pop dent. For the color ramp, use a ramp that only uses shades of one color. Let's choose blues. At the bottom, you will notice the mode being used. This is how QGIS classifies the data. There are many options and you should choose the method that best illustrates your data. You can check the histogram to help you decide which method to use. To open the histogram, select the histogram tab and select load values. You can see the mean value by checking the box next to it and as well as its standard deviation. Select the classes tab. In this case, let's use the mode equal interval. We can also alter the number of classes by using the up and down arrows or by setting it to a specific number. Leave the number of classes at five. When done, select classify, apply, and okay. You now have a core polyth map. For more information on QGIS, visit the UTM library QGIS playlist.