The Martinsloch is a natural arc in the mountain ridge Tschingelhörner located in the UNESCO world heritage Sardona Tektonikarena. The area, which is famous for the visibility uverthrusting rock layers, formed a slant fracture which crosses a weak black merl layer. At the crossing of the two weak layers, the Martinsloch formed by erosion. A saga tells, that the shepard Martin was throwing a spear at a giant who was stealing his sheep. He was missing the giant, but hit the rock and formed this hole. Another saga tells, that a shepard from Glarus fell in love with a dairymaid from Graubünden in the Martinsloch at 11th of November, the Martinsday. The Martinsloch is also used as a natural calendar: twice a year, the sun shines through the hole onto the church of Elm which marks the begin of spring and autum. It is belived, that is was a prehistoric observatorium and that the Christian church was build on a celtic sacred site.