yellowstone geyser
An investigation is underway at Yellowstone National Park after an employee discovered a foot in a shoe floating in the Abyss Pool (above) on Tuesday
Yellowstone National Park officials are investigating after an employee spotted part of a foot, in a shoe, floating in a hot spring in the southern part of the park, officials said Thursday.

Tuesday's discovery at Abyss Pool in Wyoming led to the temporary closure of the West Thumb Geyser Basin and its parking lot. The area has since reopened.

The park did not have any other information about the investigation to make public on Thursday, park spokesperson Morgan Warthin said.

Abyss Pool, located west of the West Thumb of Yellowstone Lake, is 53 feet deep and the temperature is about 140F, park officials said. It is on the south side of the southern loop through the park.

In such hot springs, superheated water cools as it reaches the surface, sinks and is replaced by hotter water from below.

The circulation prevents the water from reaching the temperature needed to set off an eruption like happens with geysers in the park, according to the park's website.

The park is mostly in Wyoming, but spreads into portions of Idaho and Montana.

It's unclear how long the foot has been place in the hot spring - but the strange discovery comes two months after the park closed in June after rivers across northern Wyoming and southern Montana surged over their banks following heavy rainfall.

The rainfall exceeded five inches in parts of the park, and accelerated the spring snowmelt - which then brought another five inches of liquid.

Park officials characterized the severe flooding tearing through the region as a once in a 'thousand-year event,' that could alter the course of the Yellowstone river and surrounding landscapes forever.

About 10,000 tourists were evacuated - including a dozen trapped campers who were rescued by helicopter - emptying the park completely of all visitors.

Photos and video the park uploaded by park official showed mud-mixed water surging through sections of road that had been knocked out due to the flooding, and subsequent mudslides and rockslides.

Houses in surrounding communities were flooded or washed away by streams that turned into raging rivers, roads have been carved away, and bridges have collapsed into the torrent.

The park partially reopened in mid-June as visitors flocked back to the park. About 2,000 to 3,000 vehicles entered the park within the first few hours it opened, according to officials.