THE limestone formations around many hot springs are not as haphazard as they appear.
Geothermal ponds and terraces like those at Mammoth Hot Springs in Yellowstone National Park, Wyoming (above), are built up when calcium carbonate-rich spring water depressurises and cools. Carbon dioxide bubbles appear, which trigger the deposition of a mineral called travertine in layers that can grow as quickly as 5 millimetres per day.
Some suggest that heat-loving microbes in the water influence the shapes of the resulting terraced ponds, but John Veysey and Nigel Goldenfeld at the University of Illinois, Urbana-Champaign, say that a number of purely…
