An erupting geyser is said to be a breathtaking natural spectacle. But it's probably a lot less so when it starts raining down decades of garbage.

In its biggest blow in over 60 years, Yellowstone National Park's dormant Ear Spring blew its top, erupting scalding hot water over 9 metres (30 feet) into the air on 15 September. And with it, it brought a rain of debris thrown in by tourists since perhaps the 1930s.

"After Ear Spring erupted on September 15, employees found a strange assortment of items strewn across the landscape around its vent!" Yellowstone National Park wrote in a Facebook post.

"Some are clearly historic: they'll be inventoried by curators and may end up in Yellowstone's archives."

Among the items, National Park employees found cans, part of a cinder block, crumpled foil, a plastic cup and spoon, cigarette butts, a sign that seems to have something to do with bears, a whole lot of coins, and a baby pacifier from the 1930s.

yellowstone geyser junk(Yellowstone National Park)

The park has experienced a renewed frenzy of thermal activity on Geyser Hill where Ear Spring is located in recent weeks. This includes new vents and surface fractures, and a "new thermal feature" that has led to the closure of a popular boardwalk in the Upper Geyser Basin to prevent people from being splashed by the boiling water.

Situated over a volcanic caldera, Yellowstone is famous for the activity of its hot and acidic springs. Whenever there is a spurt of thermal activity, speculation arises that the volcano is about to blow.

There is, however, nothing to worry about in this case.

"Changes in Yellowstone's hydrothermal features are common occurrences and do not reflect changes in activity of the Yellowstone volcano," reassured the US Geological Survey.

"Shifts in hydrothermal systems occur only the upper few hundred feet of the Earth's crust and are not directly related to movement of magma several kilometres deep. There are no signs of impending volcanic activity.

"There has been no significant increase in seismicity nor broad-scale variations in ground movement."

It does, however, remain strictly against the park's rules to throw your garbage into the geysers, and not just because littering makes you a trash person.

"Foreign objects can damage hot springs and geysers," Yellowstone National Park said. "The next time Ear Spring erupts we hope it's nothing but natural rocks and water.

"You can help by never throwing anything into Yellowstone's thermal features!"