Useful Information

Location: Grosses Tschingelhorn, Near Elm, Sernftal, Glarnerland.
Open: No restrictions.
Fee: free.
Classification: SpeleologyKarst Cave
Light: n/a
Guided tours:
Bibliography: Marco Bischof (1993): Das Geheimnis des Sonnenlochs, Esotera Nr.8 (1993) S.90-95
As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
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Die Tschingelhörner und das Martinsloch; 22. Juli 1812. Painting by Hans C. Escher von der Linth

The Martinsloch (Martin's Hole) is - as the name says - a simple hole. The cave which runs through a mountain side, forms a sort of natural bridge high up on a mountain, the Grosses Tschingelhorn (2,850 m asl). It can easily be seen from the last village at the end of the Sernftal, which is called Elm and is located about 1,000 m asl. The mountainridge to the southeast is called Tschingelhörner, actually the plural form of Tschingelhorn, and the Grosses Tschingelhorn is the biggest, as the name says. The Martinsloch is 17 m high and 19 m wide, located 2,642 m asl right below the ridge.

This cave is not famous with speleologists, but with astronomers and any kind of esoterics. The sun shines through the hole and thus creates a bright spot wandering across the valley over the day. The church of the village of Elm was built on a spot where two times a year it is hit by the sun falling through the hole. The first is one week before the astronomic beging of spring on 13-MAR and 14-MAR at 8:53 CET. The second time is one week after the astronomic begin of autumn on 30-SEP and 01-OCT at 9:33 CEST. The church is illuminated for about 2.5 minutes, then the bright spot has moved over the church. Obviously this works only on good weather days. If there is a little fog or haze in the air, a clearly visible five kilometers long ray of sunlight can be seen, before and after the ray hits the church.

The beam of light effect works not only with the sun, but also with the moonlight. However, the moonlight is not bright enough to shine on the church. It is necessary to know where it will be seen and to look towards the cave to see it. And as the moon follows a much more complex path, the dates are not regular. The exact dates and locations are computed by astronomers and the then published by the local tourist information.

And there is another interesting aspect of the Martinsloch. The cave is located at a famous geologic spot, as here important mechanisms for the formation of Alpine mountain ridges were detected. In this time mountains were a result of the shrinking of earth, because of it cooling down. Similar to an old apple the surface becomes wrinkles. But here is a strange place, where older rocks lie on top of younger rocks. Simple geometry tells us, that there are two possible movements which can cause this: a packet of rocks is turned upside down, and a packet of rocks is moved on top of another almost horizontally along a ramp-like fault. Both are dynamic movements, which differed much from the common view on mountain formation.

The story begins with Hans-Conrad Escher von der Linth (*1767-✝1823), who discovered older greywacke above younger limestone in the Glarn Alps around 1809. He did not draw any conclusions, but he was the first who discovered such a strange thing. His son, Arnold Escher (*1807-✝1872) was Professor of geology at the Polytechnikum Zürich, and started in 1940 to work in the Glarn Alps. He writes about this in 1941, tells about both above possibilities, but has not believe enough in his discoveries to formulate them. But in 1848 he guided his British collegue Sir Roderick Impey Murchison and he immediatle formulated the theory of a thrust fault, a huge packet of rock moved by tectonic forces. Escher was never self confident enough to stand for such a new theory, so he asked him not to publish this theory and invented a much less innovative and complicated theory called Glarner Doppelfalte. This theory explained much, but also prevented further development in the theory of the formation of the alps. However, in the early 20th century the thrust fault structure of the alps finally became evident and is today well established. It is actually a part of the modern plate tectonics.

So what has all this to do with the Martinsloch? The Glarner Überschiebung (Glarner thrust fault) is right above the cave. The cave is located in the lower but older rock, the peaks of the mountains are formed of younger rocks. The rock were moved some 40 kilometers to the north relative to the rocks below. The engraving shown on this page displays this very impressive, although its creator did not belive in the theory himself.