I always loved geology and geography when I was in school and have kept up my interest over the years. Living in Arizona, we've got plenty of interesting geography, from mountains and deserts to fascinating road cuts and huge canyons that reveal geologic ages gone by.

Now, someone has created what I would say is the ultimate app for Geography/Geology amateurs and professionals.

I've been using Geology AZ, [iTunes link] which for US$4.99 overlays a whole lot of information on a basic map of the state. You can add town and cities, roads, counties; you know, the usual stuff you find on maps. Then you can dive much, much deeper, with maps of new and old fault areas, earthquake sites, old and current mines, public lands, fire history, and nicely rendered terrain elevation maps. I'm just scratching the surface here, so to speak. You can go to the developer web site and get a lot more information about what is available.

You use standard finger gestures to zoom in and out, and the level of detail is amazing. The items on the map are color coded, so you can tap something and get a lot more detail. You can use the iPhone's built-in GPS to plot your position on the map, and find out all sorts of interesting features that are near you. Thankfully, I'm not living on a fault line.

You can also capture one of your custom maps and output it in high resolution to your computer. If you're not interested in Arizona there are currently maps of Oregon/Washington, California, Texas, Florida and New York, with other states on the way. You can check them out here.

This is a great tool for education, enjoyment, or a heads-up about what geological formations or geographical highlights are near you. You can change the transparency of each layer, superimposing data across several layers of the map.

I can't say enough about how clever this app is, and the price is very reasonable considering the mountains (pun intended) of data it contains.

The Arizona map data is about 42MB, and using the app does not require any data from your cell provider. It runs on either the iPhone or the iPod touch, but getting a GPS fix is only possible on the iPhone.

Check the gallery for some screen shots and click here to see a video of this app in action.: