TARIOMTIC DIABASE OF THE FICHTELGKBIRGE. 53 



dichroic grouridmass. An oxaniination with higher magnification 

 shows in this chk)iopitic groundmass numerous scattered, opaque 

 white granules and large numbers of minute needles of actinolite ; 

 the former frequently occur in lines which curve round the varioles. 

 The varioles themselves are so much altered that their original 

 structure cannot be fuUj' determined. The resemblance of the 

 alteration-products to those of the variolite already described 

 suggests a ccmmunity of composition. The varioles are now an 

 opaque dusty mass charged with lines of granules and needles of 

 ilmenite, while in places there are transparent areas of a dolomitic 

 mineral traversed by numerous needles of apatite. The opaque dusty 

 material is probably a kaolin resulting from the decomposition 

 of the felspathic microliths or giobulites, while the dolomite and 

 ilmenite are the products of the alteration of the pyroxene. The 

 true radial arrangement of the Eerneck varioles is absent, and the 

 only approach to it is due to the disposition of the secondary 

 ilmenite needles. The whole structure of these spherulites shows 

 that they are more primitive than the others, and due to a more 

 rapid and imperfect development. 



Returning along the south side of the tongue of diabase we 

 can trace the junction with the Devonians across the crag already 

 described, and beside the tree-covered bank that separates two fields 

 of shale and grits, to the summit of the Miihlleite. Just on the 

 brow of the hill a brecciated limestone crops out across the field, 

 and is succeeded by beds of shale wiih calcareous nodules (Middle 

 Devonian). This series of sedimentary rocks can be traced away to 

 the north-west down the steep slope to the Oelschnitz, across the 

 stream, and up the opposite bank. It forms a slight depression, 

 bounded on each side by a rib of diabase ; that on the north-east 

 side of the Devonians is the more conspicuous, but that on the 

 south-west is spheroidal in one place, a few feet from the junction. 

 A. section through this has been cut in making a wood-cutters' road, 

 which ends abruptly on the Devonian band. The diabase is less 

 amygdaloidal, and is more regularly variolitic, than when in imme- 

 diate contact with the clastic deposits. Along the line of junction 

 the inriuence of contact-alteration can be seen in the Devonians ; 

 the shales are indurated, baked, and iron-stained, and the limestone 

 brecciated and marmorized. 



The same contact-phenomena, both in the development of a 

 variolitic structure and the alteration in the sedimentary^ deposits, 

 can be seen round a similar tongue of diabase that projects from the 

 Miihlleite a little further to the north-west, and runs for some 

 distance towards the south-east into the Devonian. 



Except for an occasional band of Devonian that stretches across 

 the ridge, the whole of the south bank of the Oelschnitz and the 

 Metzlersreutherbach in this area is of the ordinary amygdaloidal 

 diabase. 



Having descended from the Miihlleite to the Oelschnitz, one 

 turns to the steep left bank of this river in the hopes of finding 

 a better section than the few scrappy exposures previously noticed. 



