Object Class: Safe


Map of the Western Interior Seaway during the Cretaceous period, overlaid onto North America

Special Containment Procedures: Due to the depth of SCP-XXXX, only standard access site security and maintenance regulations apply. No researchers or MTF agents are allowed to enter SCP-XXXX. All exploration is to be conducted via Remote Operated Vehicle.

Description: SCP-XXXX refers to a series of salt-water filled caverns located roughly 15 kilometers underground, located approximately under the same are occupied by the Western Interior Seaway 80 million years ago. SCP-XXXX has an approximate overall volume of roughly 25 million square kilometers, with individual caverns ranging in volume from roughly 1,000 cubic meters or less to the largest known, which has a volume of three hundred thousand cubic kilometers. These caverns exhibit large amounts of hydrothermal activity far away from any major tectonic boundaries, leading to an unusually robust ecosystem that is one of the most notable features of the area.

The ecosystem of SCP-XXX is composed of organisms that are otherwise extinct, from eras ranging from the Edicarian period to the Early Holocene. Many species that have been found should be out competed by other, more well adapted species, for reasons currently unknown. All organisms have adaptations for the environment that are not suggested in either the conventional fossil records or materials that the Foundation has access to, including gills on otherwise air-breathing organisms, bioluminescent organs, eyes that are either missing, atrophied, or hyper sensitive to cope with the low light situations.

An anomalous effect discovered during the initial entrance into the caverns is the evolution or devolution of any organism not currently capable of surviving inside SCP-XXXX into a form that is. The most common alterations for organisms brought into the environment are gills for air-breathing organisms, and a decrease in how firm the muscles are, to a more pressure tolerant, and somewhat gelatinous, state. Organisms changed in this way will typically attempt to fill the same niche they did in their previous environment, though if this is impossible (such as in Test-SCP-XXXX-12, where an Orchid (Taeniophyllum sp.) was used), the Organism will alter radically into a form fulfilling a niche that may not bear any resemblance to its original one (In the aforementioned test, the Orchid, when released into a vent area, quickly took root and formed a structure of capable of storing bacteria in the most chemically rich areas of the vents).

Discovery: SCP was discovered during a Foundation deep drilling expedition to construct a containment location for SCP-████, underneath central Kansas. Underneath the interference caused by the Ogallala Aquifer and the oil deposits in the region, SCP-XXXX was detected by seismographs, and later Foundation Ultra Deep Borehole 12 was created to gain access to what was then known as Subterranean Abnormality ████. After exploration, the location gained an SCP designation and the Borehole became a part of the new Site 723.

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