Mammoth Lakes Basin including the treekill area next to Horseshoe L...

The gray area along the edge of Horesehoe Lake (lower right) is one of several areas around Mammoth Mountain where trees were killed recently by high concentrations of carbon dioxide gas in the soil. Mary Lake (left of center) is the 2nd largest in the basin. The largest lake, Duck Lake, is accessible only by foot and is hidden from view.