Kluses and Related Forms in the Swiss Jura Mountains – It is shown that the usual theory of the genesis of the "kluses" (transverse gorges cutting across ndges) in the Jura mountains of Switzerland by fluvial erosion by antecedent rivers is untenable:<br> 1 st. the erosive power of a river on its bed is by at least a factor 100 too small to abrade solid rock as found in the kluses 2nd. the orientation structure of the segments of the rivers flowing in the kluses is non-random which, by the tenets of the principle of antagonism in landscape development. is indicative of a non-exogenic origin of them.<br> 3rd. the orientation structure of the klus-nvers agrees with that of the joints in the area.<br> 4th, in view of the fact that the joints are known to have been caused by recent plate-tectonic processes, the same must be assumed for the kluses: the latter owe their genesis to complicated geologic lineaments, folds and shear faults. This fact has practical consequences: During the construction of tunnels underneath a klus one has to take into consideration that the disturbance in the landscape represented by a klus my well reach geologically far into the basement. 5th,the erosion of the kluses oecurred in parallel to the direction of the joints. In this instance, the debris produced by the tectonic processes and by frost action was removed by the mechanical and chemical action of the water. During the cold times and cold spells during warm times this water was mainly melt-water.<br> 6th, special studies are necessary for the determination of the quantity of debris that was removed. The time-span available for this removal is much longer than commonly assumed: it begins with the first tectonic foldnig, in the Jura mountains already in mid-Miocene, 15 Ma ago.