Here is an example of a simple kml we made to show the locations and related data of published geochron in Las Vegas Valley.

I used the Google Spreadsheet Mapper application to create 'virtual unit descriptions' for a favorite map area near Laughlin, NV. Here's an example of what it looks like...in using the kml file, the POIs can be clicked to open up the balloon with the text. If the kml is built from scratch, there is a lot of flexibility.