On the southern edge of the Salton Sea, you'll find these. Has anyone been here? Known as mud volcanoes, mud pots, or gryphons, they give clues as to what's going on under the surface. Just a few thousand feet underground is a patch of magma about 20 miles long, 4 miles wide, and more than a mile thick. The heat from the magma causes carbon dioxide and water to bubble up through the ground. This area contains so much CO2 that it used to be harvested to make dry ice. Today, geothermal plants tap