10 GEOLOGICAL MEMOIRS. 



by the parallel lines of hornblende ; these not unfrequently in their 

 unvarying horizontality pierce far into the crystalline limestone, which 

 generally has quite a sharp line of junction with the gneiss. Still 

 there are apparent sometimes small distu^rbances of the stratification 

 very near the limestone, which at one place indeed sends out a small 

 vein-like projection into the gneiss. 



This limestone can scarcely be termed marble, it is so coarsely 

 granular. The numerous quarries afford favourable opportunities 

 for mmeralogists to search the limestone well for minerals ; and the 

 following occur in considerable abundance. Garnet. Vesuvian. 

 Scapolite. Augite. Chondrodite. Spinel-ruby (Pleonaste). Felspar, 

 with a greasy lustre and of a greyish colour. Mica, light greenish 

 grey ; rare. Sphene. Magnetic iron. Magnetic pyrites. Molyb- 

 denum-glance. Garnet and vesuvian occur in very numerous crystals, 

 some remarkably large and fine, and form conjointly a coating to the 

 limestone enclosed in the gneiss. Just as we found these minerals 

 developed at Gjellebak, Drammen, &c., on the contact-surfaces of the 

 clay-slate and the crystalline limestone, we find them here aliso at the 

 junction of the hornblendic gneiss and the marble. The extent of 

 the coating to the marble lying within it is, however, very different. 

 In the smaller bands of limestone, which are scarcely more than a 

 few fathoms in length and a few feet or ells in breadth, the garnet 

 and vesuvian generally increase so much in qaantity that they almost 

 pass through the marble band. It is quite otherwise with the lime- 

 stone beds on the eastern side of Torisdal River, opposite the Eeg 

 Palace, that have a considerable thickness, and are worked in quar- 

 ries. In these the coating is very limited and indeed in some places 

 is quite wanting. By close examination of the edge of the garnet 

 and vesuvian, we can see that the crystals of vesuvian are placed 

 immediately on the gneiss, and that their free extremities project into 

 the marble ; and this is likewise the case with the garnet crystals. 

 But where the two occur together, the crystals of garnet are always 

 placed on those of the vesuvian. That the formation of the garnet 

 is of a later date we also perceive clearly, as we sometimes find crystals 

 of vesuvian penetrated by small garnet veins ; and this is the more 

 readily seen, as the garnet is always of a brownish-red colour, and 

 the vesuvian is greenish-brown or brownish-green*. It is worthy of 

 remark also that the gneiss in the vicinity of the marble is frequently 

 traversed by streaks and lines of garnet, whilst the vesuvian on the 

 contrary is never fomid within the mass of the rock. When scapho- 

 lite crystals occur, they are usually set between the garnet and the 

 vesuvian on the gneiss ; but smaller isolated crystals are also found 

 disseminated here and there in the limestone. The crystals of sphene 



* At the before-mentioned locality in the vicinity of Vestfosser, where vesuvian 

 has been developed on the contact-surfaces of the Transition clay-slate and the 

 limestone, some garnet is also occasionally met vrith ; and here the same condi- 

 tions hold good with respect to colour, as well as to the respective time of the 

 formation of these two luinerals. A more exact chemical examination of garnet 

 and vesuvian thus occurring together would be of great interest. 



