The first screencast shows how to identify landmarks for matching your overlay to the information in Google Earth.  You need to identify at least three landmarks that the image shares with what is visible in Google Earth.  For this overlay, I chose three towns -- Fittstown, Sulphur, and Davis, Oklahoma.  They are all small towns that are marked on the hydrology map. 

I added placemarks to Google Earth for each of the towns.  For the scale of the map that we’re overlaying here, small towns work.  Large towns wouldn’t offer a specific enough location, but anything smaller would work fine, like identify the locations of streams, roads, waterfalls, or specific buildings.  The map we’re using is also marked with latitude and longitude.  That’s helpful information as well, and we can use it to check our work.

Before watching the video, make sure that both Google Earth is open and that your web browser has a second window open to the Arbuckles Hydrology map image posted to Picasa.  Clicking on this link will open to the appropriate Picasa webpage in a new window. 

As you watch, or after you watch, the video identify three points that the two maps share.  If they aren’t very obvious within Google Earth, add placemarks.