London, March 17 : Scientists have built a computer model that suggests the terraces at Mammoth Hot Springs in Yellowstone National Park, Wyoming, US, grow by a process of drowning.
According to a report in New Scientist, John Veysey and Nigel Goldenfeld at the University of Illinois, Urbana-Champaign, built the computer model.
Geothermal ponds and terraces like those at Mammoth Hot Springs 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 Veysey and Goldenfeld said that a number of purely physical processes are responsible.
The pair suspected that one of the primary processes governing the sizes and shapes of the ponds was a process of drowning.
The lips on the edge of some terraces grow faster than others due to variable water flow. This means faster-growing ponds will drown the adjacent slower-growing ones.
Using such observations, the researchers built a computer model that predicted how the terraces at Mammoth Hot Springs would grow.
Over two years, the prediction matched the appearance and distribution of pond shapes at the springs.