Handkerchief Pool was a visitor favourite for its ability to pull in handkerchiefs and return them washed and clean. (NPS photos)
Visitors could put a handkerchief into it and watch it disappear into the water, according to National Park Service. One of them was Handkerchief Pool, a small spring in the Black Sand Basin. The item would then come back to the surface after being moved through the pool’s water currents. Vistors believed the items came back scrubed and clean.
Handkerchief Pool’s activity eventually stopped in 1926. Before the road near it was diverted in 1971, visitors threw coins, rocks, logs, bottles and clothing into the spring. The story of Handkerchief Pool did not end with the 1929 cleanup. In 1950, park geologist George Marler cleaned the spring again, removing the log and gravel that had washed into it.
A log was shoved into the pool’s vent, blocking the feature and stopping the movement of water that produced its unusual effect, according to Yellowstone Science. But visitors did not limit themselves to handkerchiefs. Over time, people began putting other objects into the pool. This gradually turned a natural thermal feature into a collection point for rubbish and other items and started to interfere with the pool’s natural activity. Visitors, however, continued to throw objects into the pool even after it stopped working properly. The problem was not limited to the log. The pool had accumulated a large amount of material over the years. Objects that visitors had thrown into the water remained inside the feature, adding to the blockage and making it harder for the pool to function normally. Morning Glory Pool in the Upper Geyser Basin was another heavily affected thermal feature. Repeated cleanups removed some of the material, but continued additions clogged the vent. The pool’s temperature may have fallen, allowing algae to grow, although Yellowstone geologists noted that natural causes may also have contributed to the change. Water flowed into the pool once more, but the feature had been permanently changed by its long period of inactivity, with algae mats spreading onto its rims.
