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On the Constitution of the Territory of Rome, z&ith some Gene- 

 ral Observations on the Geognostic Character of Italy. By 

 Professor F. Hoffman. With a coloured Map. 



A. Peculiarities of the Roman Territory, arranged according 

 to the Differences of the Formations. 



The rock formations on which Rome stands, are extremely 

 worthy of the attention of the geologist. Few parts of Italy, 

 certainly few of those which have been thoroughly investigated, 

 contain, in so comparatively narrow a compass, such numerous 

 and varied phenomena, and which are of so much importance 

 with regard to the history of this earth ; and, if Leopold von 

 Buch, upon these grounds, was justified in saying, on his first 

 examination of this country, that this classical spot was as im- 

 portant to the naturalist as to the historian ; this assertion has, 

 since then, been only the more confirmed, since we have here 

 before us a district which has repeatedly, and for a length of 

 time, occupied the talents and acuteness of so excellent an ob- 

 server. The inquiries of Leopold von Buch himself, the pre- 

 vious incomplete exposition of Breislak, which has been in part 

 set aside by his successors ; and, above all, the laborious I'e- 

 searches of the meritorious Brocchi, upon the Roman territory, 

 will all be welcome and instructive guides to those who shall in 

 future direct their attention to a subject still by no means ex- 

 hausted ; and the aim of this memoir will be fulfilled, if we suc- 

 ceed in presenting a compressed, but clear view, of the most im- 

 portant geognostical relations discovered by the foregoing natu- 

 ralists, to the judgment of the reader. 



We shall commence with a relation of the individual facts eli- 

 cited by the labours of these distinguished philosophers ; and 

 then proceed to deduce those conclusions to which these ele- 

 ments may lead us. But it will be, perhaps, most in accord- 

 ance with our design, first to make the following observation. 



A single glance upon the form of the surface of the space 

 included within the walls of ancient as well as modern Rome, 

 informs us, that we may conveniently regard this little territory 

 as formed of three quite distinct portions. A broad open val- 

 ley, intersected by the numerous windings of the river; on the 

 right, a high, uniform, and nearly continuous chain of hills. 



