Batholithic Civilisation, The

Unnamed species: HIE201NPE; an extinct civilisation that took refuge in bunkers deep in their planet's crust

Batholithic bunkers
Image from Steve Bowers
YTS 9969-0091-443b, a large PostGaian world 4300 ly from Sol near the giant star 6 Geminorum, was first reached by a Metasoft explorer ship the Lightscribe in 8679 AT. This entire region is dominated by the bright red giant, a star very similar to Betelgeuse in size and age, which appears like a brilliant red spot in the skies of this world despite being 40 ly away.

From orbit the world showed no sign that life had ever existed there. Most of the original atmosphere had been lost to space, and volcanic outgassing had produced a thin replacement atmosphere of carbon dioxide and nitrogen. The surface showed signs of exposure to a nearby gamma-ray burst nearly a billion years before, since which time the local star, which has a high proper motion, has travelled far from its original location relative to the local galactic standard of rest.

This star, YTS 9969-0091-443, is on the verge of leaving the Main Sequence, and its increasing heat has evaporated all the oceans of this world; plate tectonics on the planet has ceased, preserving many ancient geological structures on and beneath the surface. One distinctive feature of this planetís geology is the presence of numerous granitic batholiths beneath the surface, domes of igneous rock which have raised the local topography but not broken the surface.

During the customary detailed deep-scan of the entire planet, the Lightscribe found intriguing density anomalies within several of these batholiths. Regular and semiregular patterns consisting of collapsed voids and regions of higher density, all at a depth of around 12 km, seemed to indicate the presence of artificial structures. These anomalies were mapped in detail by geophysical scanning before any attempt to reach them was made. Complex looping structures, apparently built in many stages and interpenetrating each other, were found in many locations, some connected to each other by long collapsed tunnels, others very small and with no sign of newer additions.

In 8844 several teams of deep mining vecs and provolved Rheolithoids began to explore the tunnels in person. The collapsed tunnels had once contained a very salty solution of water at high pressure, and at length they found the fossilised remains of creatures which had once inhabited these voids. Segmented shelley creatures resembling armoured worms, each with many appendages extending from their ventral and dorsal surfaces, were found in the larger chambers of these tunnels, among fossilised remains that may have been biological machinery of many kinds. This species was given the label HIE201NPE by the Hamilton Institute, who were assisting the excavation via teleoperated devices controlled from the surface.

The remains of HIE201NPE have been extensively studied since that time, and the gamma ray burst which caused their seclusion has been reliably dated to 942 million years BT. For several million years before that date they existed entirely beneath the surface of this planet, in numerous isolated water-filled caverns, and appear to have originally been a surface-dwelling species which retreated underground to avoid the radiation from a nearby hypernova. They may have originally been a water-dwelling species, but they modified themselves so extensively in order to survive the high temperatures and pressures of the batholithic environment that it is impossible to tell. No remains of surface life have been found on this planet, either because of the extreme environmental degradation left by the burster, or possibly because of a visit by the mysterious Restorers at an unknown date.

Underground, the separate and isolated bunkers of this species seem to have developed into new cultures that differ quite significantly; many died out within a few years or decades of the hypernova event, while others persisted for far longer, drawing power from geothermal gradients. The surviving bunkers would often extend their tunnel systems into nearby territory, sometimes abandoning old tunnels and rediscovering them millions of years later. On occasion two separate bunker cultures would meet, an event which sometimes led to the destruction of one culture by another by genocide or absorption, or sometimes to an apparent cultural renaissance and a new, stronger culture that persisted for millions of years. The last bunker died out 921 million years ago, a ragged remnant of a civilisation that had once spread though half a continent.

This species were highly skilled in biotechnology, and almost all there remaining artifacts are biologically based; unfortunately this means that little usable information can be gained from these machines, as regional metamorphosis and hydrothermal crystallisation has destroyed most fine structure almost everywhere. There is little evidence of symbolic representation on the walls of the tunnels or on the artifacts, although Hamilton Institute archaeologists maintain a record of the enigmatic scratchings found in the newest tunnels in case they may one day be deciphered.

There is little evidence that the species ever attempted to regain the surface; a few exit tunnels date from the very early era of the batholithic confinement, but they were swiftly abandoned, presumably because the conditions on the surface were so bad. Later the species seems to have become dependent on the heat and pressure of the depths, and avoided the cold, low pressure regions above, where their blood would boil. Some evidence of later tunnels to the surface exists, presumably used by biologically modified members of the species; but the upper reaches of these tunnels have been obliterated, apparently deliberately.

Perhaps one or more surface colonies was established by this civilisation at some point, but all evidence of this has disappeared, perhaps due to erosion of the surface during the last stages of tectonic activity or due to Restorer action. It is even possible that species HIE201NPE managed to leave the planet and establish colonies elsewhere, and some non-mainstream archaeologists have interpreted the mysterious wall-scratchings to be descriptions of such interplanetary and interstellar missions, but no other evidence of such missions has been found. Because of this starís high proper motion it is unlikely that the stars that were nearby at the time can be reliably identified.
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Text by Steve Bowers

Initially published on 21 February 2012.