Tootfinder

Death Gulch at Yellowstone is "a natural death trap for animals" due to CO2 and H2S accumulation. "At high concentrations..., these gases are lethal, and the death of one animal is thought to lure in others, who are then also overcome." Also, description of Wahb Springs.
Great post by US Geological Survey #USGS scientists

Yellowstone’s Wahb Springs and Death Gulch—unusual features with unusual names
In the northeast part of Yellowstone National Park there is a thermal area with a strange composition. And even stranger names.