Yol. 52.] DEPOSITS, ETC., IN STJB ALPINE SWITZERLAND. 



571 



•original bed, which lay probably in the direction indicated in the 

 eketch-map by a dotted line (fig. 8). Of this, proof is afforded by 

 & remarkable exposure at Kaltboden, on the left bank of the present 

 Sihl, about 1 kilometre above Schindelleggi, close to the railway and 

 road leading to Einsiedeln. As is shown in the diagram (fig. 9), 



J?ig. 9. — Section at Kaltboden, near Schindelleggi. 



-50 m-. 



talus i^MM ^»tfe, 



1 ""^^^^^S^feSk 



the section exposed in the large pit at contour 320, about 10 metres 

 in depth, consists in its lower part of alternating layers of fine 

 gravel, sand, and clay, dipping in opposite directions, and overlain by 

 3 metres of moraine followed by 2 metres of talus. With the excep- 

 tion of a little adventitious Sernifite, the gravel is mainly composed 

 of yellow and grey limestone- and sandstone-pebbles, upon which no 

 ice-scratches are observable, while the moraine contains striated 

 boulders from the size of a man's head to 1 metre in diameter, both the 

 calcareous and polygene Miocene Nagelfluh being largely represented. 

 Below this pit, and on the same slope, along a canal running parallel 

 to the river at contour 775, another large quarry, recently opened, 

 exhibits a horizontally stratified section, 20 metres in depth, com- 

 posed of 7 metres of glacial clay and 10 metres of sand and gravel, 

 overlain by 3 metres of moraine and talus. The moraine at the top 

 of the upper as well as of the lower quarry is of the third, the clay at 

 the bottom of the lower quarry.is of the second glaciation ; hence we 

 have in the lower and upper exposure an extensive Interglacial, 

 that is, strictly fluviatile delta and superposed detritus-cone de- 

 posited by the Sihl after the second Ice-period. The floor of the 

 detritus-cone is probably not much below that of the upper quarry, 

 as is evidenced by a spring which issues a few hundred metres 

 higher up the road at contour 824. The extent of these deposits, 

 no less than the beautifully clean-cut sections, the typical detritus- 

 cone structure, and, in addition, the absolute flatness of the over- 

 lying moraine, showing the total absence of any ploughing action of 

 the glacier, combine to render the two exposures of Kaltboden 

 among the most striking and instructive of the whole district. 



Before the deposition of the Kaltboden delta, and, a fortiori, 

 immediately before the advent of the first glaciation, the course of 

 the Sihl must have been at a lower level, namely, on Molasse. That 



