L. A.Nccker de Saussure Voi/age en Ecosse. 189 



inav be collected, in which one of the sides of the stone is dis- 

 tinctly slaty, and the other distinctly granitic. There is, there- 

 fore, neither passage nor insensible transition. Here are 

 abundance of facts to demonstrate that the veins of granite 

 are not contemporaneous with the schist, but that they are 

 derived from the same mass of granite which forms the centre 

 of the mountain district of Arran. No one will pretend to say, 

 at the present day, that this mass of many leagues in diame- 

 ter is contemporaneous with the schist which envelopes it, and 

 is only an immense contemporaneous vein. If we abandon the 

 fundamental axiom of geology, that two rocks which differ in 

 their nature and stratification, belong to periods of different for- 

 mations, it is easy to perceive that the basis on which the 

 science itself reposes is destroyed, and that the edifice must 

 fall to ruins, without the possibility of ever rebuilding it on 

 solid foundations. 



" Without disputing about words," says Mr. Necker, " it is 

 enough to have shewn that the rock which constitutes the 

 lowest of the formations of Arran, is more modern than the 

 rock which is immediately placed above it, since, under the 

 form of veins, it has penetrated into the fissures of the superior 

 rock. Hence I have seen with astonishment the learned Pro- 

 fessor Jameson refuse entirely to admit the existence of veins 

 proceeding from a mass of granite, to spread themselves in a 

 superposited rock. I cannot believe that he has seen the moun- 

 tain of Tor-nid-neon, or that he has observed it with all the 

 attention of which he is capable, and with a mind free from 

 prejudice; for then he would not, two several times in his 

 Elements of Geognosy, (pp. 110 and 137.) have formally denied 

 so important a fact, and one, at the same time, so evident *." 



There are several other places in the island of Arran, where 

 the same phenomenon occurs ; for example, in the southern 

 face of Goatfield, in several portions of Glen Rosa, and in the 

 mountains which skirt the south of Glen Sannock. Mr. Necker 

 says, it may be presumed that, wherever the granite touches, 

 the mantle of slate which covers it, it penetrates this rock in 

 the form of veins. 



But the island of Arran is not the only place of Europe where 

 veins of granite or syenite have been found ; for it is to be re- 

 marked, that these two rocks are the only ones hitherto ob- 

 served, which form veins in the incumbent rocks. At the 

 foot of the granitic hills of Dartmoor in Devonshire, Mr. Necker 

 observed, in 1809, large veins of a syenite of red feldspar, white 

 quartz and horneblende, penetrate a schistous greenstone of 

 transition, composed of granular feldspar and hornblende. 

 It is in the bed of the river Elme, a mile and a half north of 



* Tom. II. p. 65. 



