114 MIOCENE LOCALITIES. 



perhaps became diverted by its bed being filled up with pebbles 

 and rubbish ; for the brook disappears in the pebble-bed of the 

 brackish-water formation,, which shows us a purely marine fauna 

 such as lives within the littoral zone. 



The brackish-water formation ceases at the distance of six 

 minutes' walk to the east of the quarry (near the Tivoli) , and it 

 also disappears at the Steinach, a distance of fifteen minutes' 

 walk to the west of the town, so that it was not of great extent. 

 Hence only a small brook here fell into the sea, forming a nar- 

 row delta which now constitutes the marl of the quarry. In the 

 sandstone rocks quarried in the deep ravine of the Sitter, near 

 the Kratzernbriicke, at Stocken, and at Kobelmiihle, as well as 

 near the Martinsbriicke and in the wild ravine of the Goldach, 

 we have a thin freshwater layer between the marine beds ; but 

 the strata enclosing it exhibit conditions varying from those of 

 the quarry, and prove that even at this small distance the de- 

 posits were differently formed. On the Sitter we have repeated 

 alternations of conglomerate, sandstone, and marl-beds, demon- 

 strating that constant changes took place in the transportation 

 of the materials of which these rocks consist, and that conse- 

 quently diverse modifications of the fauna also occurred. We 

 find, according to Carl Mayer, at the bottom, beds with oysters 

 and cones, then strata with Vcneridse and species of Tapes, and 

 still higher blue marls full of Turritella ; but the brackish- water 

 formation and the overlying pebble-bed (which is so rich in 

 animal remains characterizing the quarry) are wanting. Every- 

 where in the environs of St. Gall we meet with a peculiarly 

 constituted marine fauna, and with traces of the alternate action 

 of marine and land conditions. This is also the case if we study 

 the marine Molasse of Lucerne or of Bach. On the great sand- 

 stone slabs of Bach we not uiifrequently see the most distinct 

 ripple-marks. We meet with slabs the surface of which looks 

 as if it had been swept in one direction, and with other slabs 

 traversed by numerous interlacing undulated lines, in the de- 

 pressions of which carbonaceous particles and indistinct plant- 

 remains have accumulated, just as may be seen in the sandy 

 mud of the sea-shore; sometimes roundish impressions may be 

 observed which have been ascribed to the action of rain-drops, 



