This range of dates is the same (within uncertainty) to the single date that George Marler determined more than six decades ago.īecause lodgepole pine trees do not grow on active geyser mounds, the study suggests that when these trees grew on the Old Faithful Geyser mound approximately 650 to 800 years ago, the geyser was not erupting. To the surprise of the researchers, all wood samples had similar ages and implied that lodgepole pine trees grew on the geyser mound in the 13 th and 14 th centuries (1233-1362 CE). The specimens were then split into 41 samples and dated with the radiocarbon method. The species of the other samples could not be determined but are probably also remnants of lodgepole pine. Three specimens were identified as Lodgepole pine, which currently dominate nearly 80% of the total forested area in Yellowstone National Park. Inspired by this observation, a team of scientists collected and studied 13 mineralized wood specimens from the Old Faithful geyser mound, collected under Yellowstone Research Permit YELL-SCI-8030 and published recently in the journal Geophysical Research Letters. In one of the first applications of the radiocarbon dating method, that wood was found to be about 730 years old, with an estimated uncertainty of 200 years. In a journal paper published over 60 years ago, Yellowstone National Park naturalist George Marler described a mineralized wood sample from the mound of Old Faithful Geyser. Many of the world’s geysers are concentrated in Yellowstone’s Upper Geyser Basin, including the most iconic, Old Faithful Geyser. Transitions between activity to dormancy and changes in the interval between eruptions are often caused by earthquakes that modify the geometry of fractures in subsurface rocks and by changes in the amount of regional precipitation that flows as groundwater to geyser reservoirs. Because of the delicate balance between these controlling parameters, geysers have periods of activity and dormancy.
Natural geysers are rare because they need special conditions to form: a supply of water, recent or active magmatism to supply heat, and the right geometry of fractures in subsurface rocks to permit episodic discharge. The dates of the mineralized wood samples imply that such eruptions did not take place for over a century between the mid-13th to mid-14th centuries. Under Yellowstone Research Permit YELL-SCI-8030, 13 mineralized wood specimens were collected from the geyser mound.