NOME XIX. GBANITE AND SLATE. 



iters, and crystallised in these slits. Since 

 then the elements of granite are all capable of 

 humid crystallisation, why, as the circumstances 

 are the same, should one hesitate to acknow- 

 ledge, that it has been also dissolved and crys- 

 tallised through the medium of water ? 



" I thought then that I had made a great step 

 towards the knowledge of the formation of gra- 

 nite, when I saw with so much clearness that 

 nature could form it by the mere assistance of 

 water. My only regret was, that the proof of 

 this truth was concealed in the centre of the 

 Alps, in a spot so little accessible to the greater 

 part of the lovers of lithology. 



" But I had, towards the end of the same 

 year, the pleasure of finding the phenomenon in 

 a place well frequented, and of easy access, 

 since it is at the foot of the walls of the city of 

 Lyons. If, without the gate of the Red Cross, 

 you descend to the Saone, by a path which runs 

 under the walls of the city, you will see on the 

 right, a little beneath the fort of St. John, banks 

 of sand, the sides of which are open to the air. 

 Under these sands are schistose rocks, composed 

 of white quartz and brilliant mica, sometimes 

 red, sometimes blackish. The layers are almost 

 perpendicular to the horizon, for they form with 



