254 Geological Collections. 



remarkable fact connects itself with the discovery of an elephant's tooth at 

 Wieliezka, in the tertiary sandstone of Rzaka — a sandstone which contains 

 the Pectinites polonicus, saxicaves, and several other marine shells. We 

 see, then, that the remains of such mammifera exist not only in the sand and 

 marly clay called diluvium, as M. Cuvier and others have stated, but are found 

 already, in the tertiary period, at the same time with the palseotherium and 

 the anaplotheriura, since, in Poland, the beds which enclose them correspond 

 to those which at Paris cover the deposit containing the palseotherium, &c. 

 See M. Pusch's Memoire Ibid. 



Structure of the Environs of Roveredo, in the Tyrol. — The fertile and 

 delightful basin of Roveredo, in the Southern Tyrol, is circumscribed by high 

 mountains, composed almost entirely of Jura limestone. In the valleys of 

 this basin, however deep, no trace can be found of any rocks inferior to the 

 limestone. The more ancient formations of the Vicentine are found only in the 

 highest valleys of the Tyrol, or in the mountains of the province of Bresse. 



Upon the Jura limestone of the environs of Roveredo is seen here and 

 there a rock, similar to that which forms the crest of the mountains of the 

 Vicentine, and which is known by the name of scaglia. To this succeeds 

 a tertiary formation of some extent. The Adige has traced in the middle 

 of this basin two channels, deeply cut into the limestone ; but towards the 

 centre of the valley this river passes over a considerable portion of rocks of 

 a more recent origin. 



M. Louis Pasini, from whose paper, translated for the Journal de Geologic, 

 we make these extracts, gives a detailed account of the deposits and general 

 appearance of this district, from which he draws the following interesting 

 conclusions : — 



1. That the Jura limestone of the mountain Recoaro, and of the lake 

 Garda, dip generally E. N. E., and that the inclination is seldom troubled 

 by limited local disturbances. 



2. That the Jura limestone seems to rest at present about the mean 

 height at which it was deposited, and that the basin, crossed by the Adige 

 and the other valleys in which the Jura limestone occurs, has been formed 

 before the scaglia was deposited. 



3. That the scaglia was deposited so as to envelop, like a cloak, at once 

 the bottom of the valleys, and the sides and elevated plains of the mountains, 

 taking the horizontal or inclined form, according to the outline of the 

 inferior stratum, and connecting all the heights formed by the Jura limestone. 



4. That upon this scaglia were deposited, in succession, the tertiary beds, 

 not only along the outer flanks of the Alps, and in the plains, but also in 

 the interior valleys shut in by straight gorges, and which almost form basins. 

 Such are unquestionably the valleys of Roveredo, Arco, and Sugana. 



If we may judge from the traces of these tertiary beds which still remain, 

 it appears that they have been deposited at rather a low level, and not upon 

 all the heights, like the scaglia. 



The rocks of porphyry and granite so well known in Southern Tyrol, 

 are certainly posterior to the scaglia, as I have shewn in a paper published in 

 1825, ( Giornale di Fisica di Pavia, Juglio, Augusto, 1825. ) These rocks seem 

 to have imbedded themselves in valleys, dug in the midst of the Jura lime- 

 stone and the scaglia. I do not deny, certainly, that the strata underwent 

 partial elevations and derangements when these igneous rocks appeared ; 

 but a general view of the facts above detailed does not warrant the conclusion 

 that the elevation of our calcareous Alps above the level of the sea was 

 due principally to the effusion of these modern igneous rocks. The mica 

 schist, which forms the base of our sandy and calcareous formations, has 

 been raised to its actual height before the red sandstone was deposited ; 

 the dolerite, which has traversed it in every direction, in the form of masses 

 and veins, appears to have been alone the ancient cause of elevations. The 

 - -1 ~*»w^«tone, regularly stratified upon the mica schist and the dolerite, is 



