216 Mr. De la Becbe o?i the Differe7iccs 



taining pieces of quartz and quartziferous porphyry, he adds : 

 " These beds dip rapidly at 70° to the S. and form a promon- 

 tory in the lake (of Lugano) on which the chapel of San Mar- 

 tino is built. This rock appears in place for about ten mi- 

 nutes walk, the dip of the beds diminishing to 60°. It is then 

 covered by a compact smoke-gray limestone, in beds about a 

 foot thick. These dip as the beds on which they rest, and 

 have the same inclination on the side of the mountain; but in 

 their prolongation towards the lake, the dip continually dimi- 

 nishes, until at its level it is scarcely 20°. The beds, as they 

 rise, describe a curve that somewhat resembles a parabola. 

 The further we advance on the road, the more we find these 

 beds traversed by small veins, the sitles of which are covered 

 by rhombs of dolomite. Similar crystals are also observable in 

 small cavities of the rocks. As we advance, the rock appears 

 divided into fissures, and the stratification ceases to be distinct. 

 Lastly, where the face of the mountain becomes nearly per- 

 pendicular, it is found to be entirely formed of dolomite. 

 There is no marked separation between the limestone and the 

 latter rock. By the increase of the veins and geodes, the cal- 

 careous rock entirely disappears, and pure dolomite occurs in 

 its stead." ****** " As we advance along the high road, the 

 purer we find the dolomite, and at the same time the whiter 

 and more granular." 



" The road cut out of this mass of dolomite is not half a 

 leao-ue long. We then observe the rocks retreat, the Monte 

 Salvadore fall rapidly to the S., its sharpcrest becoming broader, 

 and chesnut-trees covering the side of the mountain, which 

 previously presented a mere mass of bare rocks. From hence 

 to beyond Melide the mountains are composed of dark augite 

 porphyry mixed v.itii epidcte, the same as it also appears at 

 Campione, Bissone, and Rovio." 



In the highly interesting geological map which M. Von 

 Bucli has had engraved at Paris within these few days*, and 

 which comprehends the lake of Orta, the southern parts of the 

 Lago Maggiore, and the Lago di Lugano, he represents a 

 small portion of mica-slate and red porphyry between the mass 



* This, like most of the other works of M. Von Bucli, is intended merely 

 for private distribution. It is to be regretted that this gentleman could not 

 be prevailed upon to give publicity to at least a considerable portion of the 

 mass of information, more particularly on geological subjects, which he has 

 by so much labour and assiduity collected together. Those indeed who 

 have the honour of M. Von Duch's ac(]uaintance have certainly no reason 

 to complain, for to them he is most liberal both of information and of his 

 works; but for thc^irogress of science generally, it is much to be lanienteil 

 that such productions as the physical description of the Canaries should not 

 be accessible to all the world. 



of 



