Zur Tal- und Reliefgeschichte des Churfirsten-Alvier-Gebietes (Kanton St. Gallen)

[摘要] The valley and relief history of the Churfirsten-Alvier ränge(Ct. St. Gallen):
Valley formation in the Churfirsten-Alvier range, between theLinth and Rhine rivers. began at the end of the Miocene withthe tectonic history of the Helvetic nappes. In early stages.the Cretaceaous sequences became independent of theirJurassic substratums and these from their Verrucano-Tnassicbasement. The valley of Lake Walenstadt in the south wasinitiated between this basement and north-moving youngersequences. The Thur valley, north of the Churfirsten range,which follows a syncline in the highest Helvetic nappe. wasfilled with early Tertiary Sediments and Pennine Flysch. TheValleys in the Alvier area are formed along synclmes andfaults in the Cretaceous sequence; these structures dip towardsthe Rhme valley.
The Churfirsten range forms a limestone shield in the Helvetic nappe. It broke up foUowing ±N/S-onented joints. Thereinbetween, excavation of kars (cirques) began already duringpre-Ouaternary glaciation; they are still intact at the ends ofthe ränge, but in the middle the kar-walls broke down alongthe steeper southern slope.
During the Mindel and Riss glaciations. no Rhine ice flowedthrough the saddles between the Churfirsten peaks into theThur valley; however, this could have been possible in pre-Mindelian cold periods at high ice levels and still lower moun¬tain relief.

[学科分类] 自然科学（综合）