The Yellowstone Plane

The Yellowstone Plane is a vast empty space in reality entirely located beneath the surface of Yellowstone National Park, Wyoming.

Discovery

1860, during the great expanse to the West of North America, many prospectors and migrants set camp around the base of Yellowstone's supervolcano. Finding protection against natives within the area, some temporary residential housing was set inside cave entrances. It didn't take long for these frontiersmen to begin following the winding caverns down to an incredibly vast space devoid of any natural light.
The entrance into this expanse is located at the north-western base of the Yellowstone supervolcano, where a carved cave tunnel system is found. The entrance appears to be naturally forming, however, there is evidence to suggest manmade tampering and engravings have also been prevalent before initial discovery.
The Klementine Company, a subsidiary of Kingfisher Limited, purchased the small settlement in 1876, removing residents from their homes for a small compensation. The company settled Outposts around the supervolcano and inside the plane. The most prolific settlement in the company is Outpost Abigail, located at the cave's entrance; becoming a central hub for employees and hired hands to begin an expedition into the great darkness facing them.

Geography

The entrance to the plane is via a singular cave entry right next to Outpost Abigail. The cave system descends 4500 feet (1.4km) leading to an open area.
The plane itself is a vastly expansive environment completely residing in total darkness, due to the lack of natural light being able to reach the depths of the plane. However, the soil inside the environment is very reactive pale sand that illuminates a greenish-hue whenever pressure is applied to it. This glowing sand is found everywhere in the plane, blanketing the environment in a thin layer. Though it does not give a large source of lighting, the sand is quite aiding for expeditions to make sure parties are huddled at all times.
Cartographers and guides who were hired by the Klementine Company, attempted to navigate the space in sheer darkness, only using oil lamps and the plane's sand as light sources. Literally bumping into surfaces as a means of mapping out the environment was not a terrible strategy in this circumstance. Through these methods, experts were able to identify various landmarks in the terrain. In its majority, almost the entire recorded environment is largely flat plains similar to sand dunes or rolling hills, but various landmarks have been noted including cliffsides, valleys, canyons, and even Manmade Structures.
Dead bushes and trees are commonly found throughout the plane, with specimens revealing ashy-colored branches that are very brittle when applying pressure onto them.

Localized Phenomena

The Yellowstone Plane is at first glance lifeless and void of life. However, there have been sightings of figures and silhouettes shifting in distances while exploring the plane, suggesting there is a viable ecosystem that is possibly inhabiting life. These figures are often reported in various sizes from human in shape to as large as an elephant. No reports of any hostilities from these entities have been forwarded.
Landscape shifts provocatively, but does return to its regular state when it was first observed and discovered. One such example is when following a preset path, landmarked by a point of interest called Adam's Tip, which was a narrow sharp-edged mountain cliff 12 klicks north of Outpost Bessie, the explorers become perplexed and alert when instead of finding Adam's Tip they found four identical landmarks instead in a surrounding manner around the party. Other instances are in which the ground will fluidly shift similar to the motions of waves, making explorers lose balance and unfortunately be buried by the sand.
There have been eyewitness accounts of attacks, most notorious being the now lost Outpost Cadence further within the plane. These attacks were reported to include inhuman creatures that burrowed in the sand and eviscerated any living presence around.
Time dilation has been a rare but terrifying discovery within the plane. In which explorers have returned several days after their initial designated return date, only to testify that they've been gone for the intended time. An unfortunate incident that was documented was Leeroy Andrews, a Cartographer who returned to camp looking physically aged by years, and later died from apparent 'natural causes.'

"The only thing guiding me through this hellscape is taking it slow; one foot at a time.
Mainly because I can't see shit all without this glowing sand around"

- Dr Andrew Fuller, Cartographer at Outpost Bessie (1877)

Discovery
June 1860
Known Locations
Outpost Abigail
Outpost Bessie
Outpost Cadence

Alternative Name(s)

Mortem

Included Locations

• The Cold Cabin

Related Ethnicities

• Plane Preacher

Contested By

• The Klementine Company