Stone Age man created a massive network of underground tunnels criss-crossing Europe from Scotland to Turkey, a new book on the ancient superhighways has claimed.

German archaeologist Dr Heinrich Kusch said evidence of the tunnels has been found under hundreds of Neolithic settlements all over the continent. In his book - Secrets Of The Underground Door To An Ancient World - he claims the fact that so many have survived after 12,000 years shows that the original tunnel network must have been enormous.

'Across Europe there were thousands of them - from the north in Scotland down to the Mediterranean.
'Most are not much larger than big wormholes - just 70cm wide - just wide enough for a person to wriggle along but nothing else. 'They are interspersed with nooks, at some places it's larger and there is seating, or storage chambers and rooms. 'They do not all link up but taken together it is a massive underground network.'

The Melott et al. study thus lays out a test for the occurrence of a Younger Dryas bolide impact, constrained by observations of the recent Tunguska impact. Their estimates, however, for the increases in nitrate and ammonium associated with a Younger Dryas–size comet are orders of magnitude larger than observed in the Summit Greenland ice core records; the Younger Dryas nitrate and ammonium increases are at most just half of the Tunguska increase. Likewise, the anomalies noted at the start of the Younger Dryas appear to be non-unique in the highest-resolution records (Figs. 1A and 1B). This may be due to the ice core sample resolution. The GISP2 ∼3.5 yr sample resolution could potentially under-sample a nitrate or ammonium increase (Mayewski et al., 1997) because both compounds have atmospheric residence times of a few years. As Melott et al. note, higher-resolution sampling from the Greenland ice cores could determine if large (i.e., orders of magnitude larger than the Tunguska event) increases in nitrate and ammonium occurred at the start of the Younger Dryas. Several other issues still remain with the bolide-forcing hypothesis for the Younger Dryas. For instance, the original Firestone et al. (2007) impact-marker records have not proven reproducible in a subsequent study (Surovell et al., 2009).

Similarly, a compilation of charcoal records do not indicate large-scale burning of ice-free North America at the onset of the Younger Dryas (Marlon et al., 2009) as put forward by Firestone et al. (2007). Another recent study showed that late Pleistocene megafauna extinctions, potentially attributable to a Younger Dryas impact (Firestone et al., 2007), significantly preceded the Younger Dryas (Gill et al., 2009). Furthermore, it has yet to be demonstrated how a short-lived event, such as a bolide impact (or abrupt Arctic meltwater discharge, i.e., Tarasov and Peltier, 2005), can force a millennia-long cold event when state-of-the-art climate models require a continuous freshwater forcing for the duration of the AMOC reduction (e.g., Liu et al., 2009). If the bolide impacted the southern Laurentide margin near the Great Lakes, it could have opened the eastern outlet of Lake Agassiz, but Great Lake till sequences are not disturbed (e.g., Mickelson et al., 1983).

In some cases writings have been discovered referring to the tunnels seen as a gateway to the underworld.