Volcan Copahue, Argentina:

The natural acid hydrothermal systems at Volcan Copahue generate low (0.5 – 2) pH fluids that form the headwaters of the Upper Rio Agrio river system. Volcan Copahue may represent a a terrestrial analog of Meridiani Planum on early Mars. It also shares clear similarities to, from chemistry and mineralogy to microbiology, with Rio Tinto.

Davis Mine, Massachusetts:

The Davis Mine, formerly the largest Massachusetts pyrite mine, used for sulfuric acid production, is now a site of lingering acid rock drainage with photosynthetic streamer-forming organisms further downstream.

Rio Tinto, Spain:

Rio Tinto is a heavily studied acid-mine drainage site in Spain that has chemical and mineralogical similarities to Mars.

Spotted Lake, Canada:

High sulfate levels, seasonal freeze-thaw cycles, and its characteristic appearance make Spotted Lake (British Columbia, Canada) an analog for ancient paleolakes on Mars: sulfate salt deposits there might offer periodically habitable environments, and may have concentrated and preserved organic materials or their biomarkers over geologic time.

Haughton Impact Structure, Devon Island, Nunavut, Canada:

Millions of years ago an impact event created this structure; while the meteorite was obliterated, the impact melt breccia remains. Gullies forming in this pulverized material are an analog for fluvial features found on Mars. We are studying how microorganisms colonize and adapt to these niches.