In+ersec+ion for Spatial People

I recently had to work with some geological maps. Although I'm not a geologist, I enjoyed their visual appeal -- who knew science could be this pretty? Here are a few samples of particularly handsome maps, along with a simple explanation of what they represent.

[Editor's note: this anonymous submission reminded me that beautiful maps are more efficient at conveying information. We did mention art a few times in the past, including GeocodedArt.com]