Graubünden is also partially located on the south side of the Alps with the four valleys of Misox, Bregaglia, Poschiavo and Müstair. Finally, the canton of Valais comprises the upper Diveria valley, located south of the Simplon Pass. Jura The Jura is a limestone mountain range running from Lake Geneva to the Rhine river. This area makes up about 12% of Switzerland's land area. Located about above sea level, this region is characterized by a limestone highland with deep river valleys. The limestone rock in the Jura is a Jurassic period rock with numerous fossils and dinosaur tracks. The name Jurassic actually refers to the Jura region where these fossils were studied at the end of the 18th century. The Jura is considered one of the most important sites for dinosaur footprints in the world. In one area near the village of Courtedoux, over 13,000 footprints were discovered in between 2002 and 2011. The range is being continually built up and decreasing in width by mountain building, accommodating the compression from alpine folding as the main Alpine orogenic front moves roughly northwards. The deformation becomes less pervasive away from the younger, more active Alpine mountain building. Structurally, the Jura consists of a sequence of folds, the formation of which is facilitated by an evaporitic decollement layer. The box folds are still relatively young, evidenced by their defining the shape of the overlying landscape (meaning they have not existed long enough to experience erosion). The folds comprise three major (lithological units) bands of building evidence dated roughly by era: the Malm, Dogger, and Lias (part of the Jurassic Geologic period). Each era of folding represents effects on a previously shallow marine environment as evidenced by beds with particular carbonate sequences, containing abundant bioclasts and oolitic divisions between layers (called horizons). The Jura Mountains rise in Swiss territory to a height of at Mont Tendre. Other high summits are La Dôle (), the Chasseron () and the Chasseral (), all located in the western part of the range, in the cantons of Vaud, Neuchâtel and Bern. Hydrology Often referred to as the water tower of Europe, Switzerland has 6% of all freshwater reserves of the continent, while only accounting for 0.4% of its total area. The country shares five river basins and some of the largest lakes in western Europe with its neighbours. It is the source of several major European rivers