Talon Fission Fumarole
This unique location periodically emitted steam for a (geologically) short amount of time. While such an occurrence isn't at all rare in nature, its cause was much more strange than one may expect. This landmark's name is a misnomer, as true fumaroles are volcanic in origin. This is not the case with the Talon Fission Fumarole.
Sometime within early Week 3, a particularly large deposit of uranium-rich minerals became flooded with groundwater. This uranium deposit in particular had a high percentage of U-235, the isotope used to generate power in a nuclear reactor. The water acted as a neutron moderator, providing the final key ingredient for a proper nuclear reaction to take place. This violent atomic reaction beneath the soil caused groundwater to boil away, stopping the reaction until it could be reignited by more groundwater. This resulted in clouds of steam rising from the ground regularly about every 4 hours, a very odd sight to see in an otherwise unassuming scrubland. This natural nuclear reactor lasted for almost a million years, only stopping when it finally ran out of fuel. The patch of land remains the same, but by the time the reaction died out, the only sign of its existence was a lack of uranium.