330 Professor Sedgwick and Mr. Murchison on the 



To the south (or towards the mineralogical axis of the Alps) the valley of the 

 Iller extends by Fischen to Ober Mieselstein, above which it is almost closed 

 in by the longitudinal ridge of the Schwarzenberg-. The river has its source in 

 a narrow glen called the Waliser Thai, and in its course by Fischen and Sont- 

 hofen, after being swollen by various minor torrents which descend from lon- 

 gitudinal gorges of green-sand, finally quits the mountains by a chasm in the 

 ridge of conglomerate above described, and falls into the plains of Bavaria*. 



On entering this valley from the north-east, we skirt the western foot of the 

 iiigh, serrated ridge of the Griinten, the lowest strata of which are composed 

 of a thick-bedded, close-grained, brown, siliceous sandstone, occasionally 

 passing into chert, and are nearly vertical. These are succeeded by bluish 

 g-reen grits, which graduate into a very hard, dark blue, calcareous grit with 

 green grains, traversed by white veins of carbonate of lime, the beds gra- 

 dually acquiring a dip of about 70" S.S.W. The weathered surfaces of many 

 of these beds present the ordinary appearances of the green-sand of England ; 

 and among their fossils Mr. J. Sowerby has recognized small casts of Ammo- 

 nites, Inoceramus concentricus, Plicatula pectinoides, TerebratulaB, two spe- 

 cies, Gryph(Ba vesiculosa (?), and a univalve very near to Cirrus plicatus. 

 These fossils are characteristic of a portion of the green-sand of England ; 

 and as the beds which contain them rest upon masses of chert undistinguish- 

 able from that of our green-sand, we have little hesitation in referring the 

 strata at the north-western base of tiie Griinten, to the lower or middle 

 groups of that formation. 



The analogy with the English series, is further confirmed by the overlying 

 beds, which are composed of a dull grey, marly limestone, containing large Am- 

 monites, and resembling the upper green-sand or malm rock of this country ; 

 these are surmounted by a thin-bedded limestone (rising into the highest peak 

 of the Griinten, called the Ilohe Wand), of a red or variegated colour, and 

 sometimes of an earthy texture, but more frequently hard, compact, having a 

 conchoidal fracture, exhibiting obscure traces of fossils on its weathered sur- 

 face, and resembling the scaglia of the southern Tyrolese Alps. In some 

 deeper sections of this mountain, there are quarries of sandstone of so bright 

 a green colour, as to form a perfect^ mineralogical ty])e of the green-sand for- 

 mation : and it deserves remark, that this rock (like certain corresponding 

 strata of our country) is used as afire-stone in the construction of the neigh- 



* We have, as a general rule, described our transverse sections in a regular, ascending order. 

 But we tliought it better, in this instance, to notice the successive phenomena nearly in the order 

 in wliich they appear, as one penetrates the chain by the banks of the Iller ; and in consequence, 

 the several deposits are described in a descending rather than an ascending order. 



