The true Geology behind The X-Files: Darkness Falls

Many of the threats encountered on the X-Files are not of this world, but even aliens seem normal when compared to some of our world´s insect species. 

In the episode "Darkness Falls" (season 1, episode 20) special agents Fox Mulder and Dana Scully are called in to investigate the mysterious disappearance of a team of loggers somewhere in the Cascade Range. Initially suspecting bigfoot (Mulder´s suspect) and eco-terrorists (Scully´s favourite), soon the agents find themselves isolated and trapped by a seemingly ancient menace lurking in the dark of the woods. Filming was done in the Seymour Demonstration Forest, north of Vancouver, a difficult to reach location even for the real film-crew.  

Soon it is discovered that an unknown species of insects was freed when the loggers illegally cut down old-grown trees. Mulder speculates that the insects, forming a sort of green-glowing swarm in the night, are a mutation caused by radioactive gases released from the underground, but extinct in the wild. However a swarm of the creatures, in close-up stock-footage of mites was used (mites are not insects, but related to spiders and can´t fly), survived hiding in the pores of a tree-ring, but now the swarm is free, very, very hungry and ready to build a nest. X-Files producer Chris Carter was inspired to write this episode based on his interest in dendrochronology – the study of tree-rings. 

Fig.1. The truth is in the tree-rings of this Douglas-fir - dendrology is used to reconstruct climate change in the past and was used in 1937 by R.H. Finch for the first time to date the activity of the Cinder Cones volcanic field in California.

But what about strange behavior of the supposed insects, are there similar real cases to be found? 

Ants are a common insect group, forming swarms with a complicated social structure and are successfully used as bioindicators - maybe even for gases coming from the underground.

 

 Fig.2. Alien ants...

Faults can be pathways for liquids and gases and some research tries to map faults by measuring the concentration of gases like radon. The permeability of a fault is also influenced by its activity, anomalous gas concentration could be signs of increased tectonic activity. During investigations in 2002 of the structural geology of the Rhenish Massif in Germany, it was noted that anthills of the species Formica rufa, F. polyctena and F. sanguinea display a peculiar linear trend. The locations coincided with active, gas-permeable fault zones. That ants could choose a site for their nest based on the bedrock is not impossible and was noted already 70 years ago, as the bedrock can influence if the soil is wet or dry and ants prefer dry conditions. However no correlation with faults or nests was known. In the 2002 research more than 1000 anthills were mapped, almost 700 of them running parallel to vertical fault lines. It´s not clear what effects the ants, as faults can imply a sudden change of bedrock, topography and gases. The case remains unsolved at the moment...

Fig.3. Ant may take some advantages by building their nests on gas-permeable faults, as the warm gases from the underground can act as sort of natural heating, figure from BERBERICH et al. 2013.

Interested in reading more? Try: 

BERBERICH, G. et al. (2013): Early Results of Three-Year Monitoring of Red Wood Ants’Behavioral Changes and Their Possible Correlation with Earthquake Events. Animals, 3: 63-84

BRENNHOLT, N. (2008): Geologische Störungszonen als Kriterium der Standortwahl Hügel bauender Waldameisen unter Berücksichtigung spezieller mikrobieller Gemeinschaften. Dissertation Universität Duisburg-Essen: 239
SCHREIBER, U.; BRENNHOLT, N. & SIMON, J. (2009): Gas permeable deep reaching fracure zones encourage site selection of ants. Ecological Indicators, 9: 508-517