210 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [DeC. 13, 



This upper and much larger division of the supracretaceous formation, 

 which so rarely exhibits fossils, is chiefly characterized by its fucoids, 

 viz. Fucoides Targioni and F. intricatus. A little to the north of 

 the turnpike and bridge over the Iller, west of Sonthofen, this 

 "flysch^' is in the condition of a light-coloured, greenish grey, mica- 

 ceous sandstone with black grains, in beds from two to four feet thick, 

 and undistinguishable from strata which I shall hereafter dwell upon 

 as the "macigno" of the Italians; one bed of it, an excellent build- 

 ing-stone, being twelve feet thick, and much resembling the " pietra 

 forte" of the Florentines. Intercalated with some of this '*macigno 

 alpin," I detected a thin course of nummulitic limestone, the upper- 

 most limit of the nummulites in this region ; for in the still higher 

 masses of *'flysch," extending by the Bolghen to the foot of the 

 Schwarzenberg nearOberMaiselstein, no traces of other fossils, except 

 fucoids, have been seen. 



It is unnecessary to say more on the mineral characters of the 

 overlying group of sandstones, limestones, calcareous grits, argilla- 

 ceous schist, and calcareous shale and flagstone, which compose the 

 flysch ; and after all the details given, I need scarcely remind my 

 readers, that everywhere in the Swiss and Bavarian Alps, where the 

 order has been preserved, this group passes downwards into, and in- 

 osculates with, the nummulite limestones above the inoceramus lime- 

 stone or chalk. When combined with the nummulitic strata (from 

 which I hold them to be inseparable) they constitute therefore one 

 of the grandest formations of the Alps, often rivaling in thickness 

 the whole Jurassic limestones, and being of as great thickness as the 

 cretaceous rocks on which they rest. 



Altered RocJcs of the Bolghen. 



Before I take leave of the valley of Sonthofen, I must explain my 

 present views respecting the phsenomena in the Bolghen mountain 

 near Ober Maiselstein, where large masses of crystalline rock (ha\dng 

 the character of mica schist, gneiss? &c.) were described* as pene- 

 trating the green sandstone, fucoid shales and millstone grits of the 

 flysch series. Judging chiefly from Scottish analogies, I formerly 

 thought that these crystalline rocks, which I then believed to be 

 of primary age, had been partially protruded in wedge-shaped and 

 conical masses through overlying sandstones and schists ; and I 

 deemed this view the more probable, as on both sides of the valley 

 of the Iller in this part of the district, the strata are not only 

 much convulsed and set on edge, but are partially penetrated by 

 eruptive rocks, and on the east side of the valley contain many 

 mineral veins. That opinion has been controverted by M. Studer, 

 who believes that those masses of crystalline rock in the Bolghen 

 are in truth transported boulders^ which were included in the 



Mosciano near Florence. Besides the prevalent species of nummulites, viz. N.pla- 

 nospira, N. millecaput, N.Biaritzana, &c., Professor Brunner thought he discovered 

 a new species, which he proposed to name N. Murchisoni. 

 * See Trans. Geol. Soc. Lond. vol. iii. p. 334. 



