218 Mr. De Li Beche on the Differences 



belemnites, ammonites, and other shells, among which are 

 Ammonites Bucklandi, sometimes of very large size, A. liete- 

 rophyllus, &c. 



A short distance south of Bellano, the general mass of lime- 

 stones and dolomite is separated from the gneiss and mica-slate 

 of the northern part of the lake of Como by conglomerates 

 and sandstones, the former of which closely resemble the Roth e 

 Todte Liegende. It contains pieces of gneiss, mica slate, &c. 

 as also pieces of the red quartziferous porphyry that appears 

 on the lake of Lugano : the paste or cement often exhibits im- 

 perfect felspar crystals ; and the whole, in fact, strongly re- 

 minds one of the Exeter red conglomerate, or Rothe Todte 

 Liegende. This rock traverses the lake, to the north of a little 

 place named La Gaeta ; the line thus separating the gneiss and 

 mica slates from the dolomite and limestone, gives that of the 

 general direction of the two latter; and it might be supposed 

 that the limestones and dolomite on each side would corre- 

 spond, as do the gneiss and mica slates on the N. : this, how- 

 ever, is not the case ; for if from Bellano we follow the eastern 

 shores of the lake of Como back to Bellaggio, we have a very 

 different section from that obtained ,by passing along from La 

 Gaeta to the same place by the western coast. To the red con- 

 glomerate near Bellano succeeds dolomite for a short distance, 

 and afterwards compact gray limestones to Varenna, near which 

 are the celebrated black marble quarries : hence to the Fiume 

 del Latto there is a continuation of the same limestones, in 

 thinner beds, with schist containing anthracite, crowned near 

 the cavern (out of which rushes the river high up the side of 

 the mountain at the latter place) by dolomite, gradually de- 

 scending to the level ot the lake opposite Bellaggio. This section 

 is then principally of gray compact limestone ; while the whole 

 of the section on the other side is dolomite, if we except the 

 mass of gypsum included in it at Nobiallo, and a few beds of 

 gray limestone south of Menaggio : there is therefore no cor- 

 respondence between them, notwithstanding the general direc- 

 tion of the rocks as shown by the red conglomerates, gneiss, 

 and mica slates, which do correspond. 



The limestones and dolomite, when stratification can be seen 

 in the latter, are highly disturbed and contorted ; and igneous 

 rocks which seem to have caused these appearances havepierced 

 through them at the lake of Lugano. 



If there be more limestones than one on the lake of Como, 

 it is difiicult to trace them ; lias at least forms a part, quite 

 different, mineralogically, from what it appears in England : 

 probably a considerable portion of these limestones may even- 

 tually be found to represent the oolite formation generally. 



In 



