English: (1 in a multiple picture album)

When I was walking through the beautiful Mammoth Lakes region and exploring all the lakes I came to Horseshoe Lake and was surprised to see all sorts of warning signs around. They were advising me of high levels of Carbon Dioxide. That would explain all the dead trees and the abandoned church.
U.S.G.S scientists detected naturally occurring Carbon Dioxide (CO2) gas in the vicinity of Horeseshoe Lake and other areas on the Mountain in 1994. Since then they have been monitoring the gas, measuring the concentration and rate of gas discharged from the ground. The higher than normal concentrations of CO2 are responsible for killing approximately 120 acres of trees next to Horseshoe Lake and elsewhere on Mammoth Mountain.
Scientists believe that the CO2 is being released from a gas reservior that has existed for a long period of time deep under Mammoth Mountain. It is believed that earthquake and magmatic activity beneath the area in 1989 opened channels for the gas to reach the surface.

CO2 is heavier than air and can collect at high concentrations in depressions and enclosures, posing a potential danger to people, especially small children and pets.