1821.] and adjoining Parts of the Continent. 45 J 



in character and composition. The Jura and English ooHte 

 being usually of a light-yellow colour, inclining to white ; while 

 the rogenstein is of a dark-brown colour, passing to dull-red : its 

 oolitic concretions are of concentric structure, and vary in size 

 from minute grains to that of a large bean. In England they 

 attain the magnitude of a cannon-ball at Sunderland near New- 

 castle, and are of a lighter colour than in Germany. 



Localities : Hall Salt Mines, near Inspruck ; near the bridge 

 of St. Maurice, in Switzerland ; Bridge, three miles south of 

 Reichenhall, in Saltzburg, on the road to Bertolsgarten. 



All these varieties of the magnesian limestone formation, or 

 elder alpine limestone, lie in the midst of, and often pass into, a 

 dark compact grey limestone. In the same limestone there 

 occur also subordinate masses of dark blue shale, and of red 

 sandstone ; these may be seen in all the salt mines of Tyrol and 

 Saltzburg, where they have masses and veins of salt and gypsum 

 dispersed throughout their substance. The gypsum is usually 

 attended with much anhydrite, sometimes forming (as at Bex) 

 the larger portion of the entire mass. The gypsum is often 

 destitute of salt, but the salt rarely (if ever) occurs unattended 

 by gypsum. Deposits of gypsum occur abundantly in other 

 strata ; but salt seems to be confined exclusively to the compo- 

 nent rocks of the magnesian limestone and new red sandstone 

 formations. 



Localities of salt : Hall, Halstadt, Halheim, Aufsee, Bex. 



Salt is known to occur in Switzerland only at Bex ; but the 

 gypsum extends from thence north eastwards in a line parallel 

 to the central chain to Leisegen on Lake Thun by the valleys of 

 Gsteig, Ander Luc, Lauenen, and Adelboden. It is found also 

 on the south-west of Bex at Val de Lie and other places on the 

 continuation of the same line through Savoy, south westward, 



IV. Transition Rocks {improperly so called,) 



Alternating; with the lower members of the mao:nesian lime- 

 • • • •» 



stone, and interposed between them and the true transition rocks 



is an important deposit which must be separated from the latter 

 class, and placed with the new red sandstone, and new red sand- 

 stone conglomerate of England, although ranged among transi- 

 tion rocks by most writers on the Alps, and by Brocchi in his 

 Account of the Val di Fassa, in Tyrol. 



This alpine formation admits of subdivision into three varie- 

 ties : 1. New red sandstone; 2. New red conglomerate of 

 England, or old red sandstone of Werner; 3. Porphyry. 



1 . New Red Sandstone, or Banter Sandstone of Werner. — The 

 component beds of this formation are seen to great advantage 

 in the Valley of the Adige, 10 miles north of Trent, and in the 

 Valley of the Avisio, which descends from the Val di Fassa into 

 that of the Adige in the same neighbourhood. In both these 

 valleys they occupy the lower regions of mountains, whose sumr 



