Geological Society. 385 



deposit near Nice, is the older Alpine limestone 3 as is the opinion of 

 M. Risso. On the authority of that gentleman, Professor Buckland 

 remarks, that near the source of the Var the older Alpine limestone 

 contains gypsum, with sulphur and salt springs; and he thinks it 

 probable, that the gypsum found near V'inaigre and Requiez, and at 

 Cimiez, belongs to this formation, rather than to the younger Alpine 

 limestone, to which Mr. De la Beche refers it. A similar devclope- 

 ment of the new red sandstone is seen between Toulon and Frejus, 

 accompanied with gypsum, saccharine dolomite, rauch-wacke, and 

 conglomerate. 



The author repeats, what he has advanced elsewhere, that although 

 limestone of all ages is occasionally more or less dolomitic, yet it is 

 peculiar to that of the new-red-sandstone formation, to be so very 

 decidedly, and almost invariably. He dissents altogether from the 

 theory which ascribes the magnesia contained in the calcareous beds 

 of the Tyrol to the proximity of trap rocks ; since he cannot conceive 

 that strata many hundred feet thick, and many miles distant, so far 

 as is known, from any pyroxenic rock, have derived from such rocks 

 their magnesian character ; — particularly as the beds, which are mag- 

 nesian, are found not unfrequently to alternate with calcareous beds 

 that are not so. 



Jan. 16. — A Letter was read, addressed to the President of the 

 Society, by MM. Von Oeynhausen and Von Dechen, containing 

 Observations on the mountain Ben Nevis, and on some other places 

 in Scotland. 



The authors of this communication, two Prussian naturalists, have 

 here presented their observations on some of the more interesting por- 

 tions of Scotland, which they visited about three years ago, with a view 

 to a comparison of the rocks of Great Britain with those of the continent. 



1. The paper commences with a description of the great barrier of 

 the Caledonian Canal : High mountains of crystalline rocks form its 

 western boundary ; conglomerate and sandstone, with subordinate beds 

 of black calcareous shale, reach from the east to the upper end of 

 Lochness ; on the banks of the river of that name, is a flat pebble 

 beach 1.^0 feet higher than the sea, portionsof which form islands that 

 have the aspect of old fortifications. 



Ben-Nevis is wholly crystalline : its summit consists of felspar- 

 porphyry; its sides of granite, which rises to the height of 3000 feet 

 above the sea, and is bordered by gneiss and mica-slate. 



Near Inverlochy Castle, a low rock projecting above the surface 

 of the bog, consists of mica-slate, alternating, as in the valley ot the 

 Spean, with gray granular limestone. 



On the N. of Ben-Nevis, sienite containing mica and hornblende, 

 both of them black, and therefore easily confounded, forms below the 

 granitic declivity a narrow ridge nearly 1000 feet high. 



On tlie rightbaiik of (ilen-Nevis, 'the schistose rocks are lower 

 towards the west, and repose on the steep side of the granite, small 

 hollows, however, intervening; they soon disappear on the north, 

 but gain ground eastward. 



A singlcsummitonlv,of(Jlen Nevis, consists of tnica-slate; beneath 

 N.S. \o\.r>.y.n.l{>. May \%'>9. 3 1) arc 



