154 Dr. F. M. Stapff — Sand-grains in Micaceous Gneiss. 



To this almost verbal translation I add Fig. 1, a copy from my 

 original survey sheets (deposited in the archives of the St. Gothard 

 K. R., Lucerne), after which the plate xxx. (northern side) of the 

 " Geologische Durchschnitte " has been arranged and lithographed. 

 It shows a longitudinal section and a base view of the bed No. 130, 

 as exposed in the top gallery of the tunnel between 7260 and 



Fig. 1. 



LonqitudiTial 



P 



&ectii 



nai'sely <itssemiiaaled:'R|rvres.'Iou'-maUne;Calc6Tuif. %, 



Apparent Strutiftcation 



t673.G" 



Top galleru ot St 

 KortVbsm 



"Tissunes 6W156E 



ijoThard tunnel 

 side (.'ioo 



7280 m. N. (Particulars, which are not relevant to the present 

 question, are omitted.) The parallel structure of the rock (S. on 

 drawing), as indicated by the orientation of the mica scales, the 

 course of the parallel quartz-bands, and the boundary faces of the 

 bed, strikes and dips N.E. and S.E., as is commonly the case on 

 the north side of the St. Gothard ; whilst the supposed stratification 

 ("mock" or "false stratification") is directed N.N.W., dipping W. 

 and E. ; and the quartz-grains are disposed in the same direction. 

 Having been accustomed to regard the "false stratification" wherever 

 it was met with in the St. Gothard as " secondary," I cannot help 

 confessing that the arrangement of the quartz-grains, in accordance 

 with the "secondary stratification," would witness against the sedi- 

 mentary origin of the bed in question. But this testimony is at once 

 overborne and reversed if we conceive that this stratification to all 

 appearance (beds between limiting faces) is here the original one, and 

 that the parallel structure (S. of drawing) of the rock is a secondary 

 phenomenon. Hand-specimens of the rock support this opinion, as 

 the mica pellicles are fitted and stretched so as to indicate a linear 



