A beautiful early fall sunset and calcite rocks in a volcanic lagoon, on the Somuncura Plateau in the Rio Negro province of Argentina. The rim of an extinct volcano can be detected around the lagoon. Photographer: Luis Argerich
It’s thought that these calcite rocks were formed by microorganisms that once thrived in the extreme environments found on the basaltic Somuncura Plateau. Weather conditions are severe here, with persistent strong winds and a very wide range of temperatures between summer and winter. Temperatures can also fluctuate considerably from one day to the next and even between early morning and midafternoon. Photo taken late in the day on March 6, 2011.