2O6 TRAVELS THROUGH 



mould a calcareous tophus, which changed after- 

 wards into a true limeftone. Then fucceeded 

 again fand-ftone, which laded but a Ihort while, 

 and was followed by the limeftone till near Civita 

 Vecckia\ where, near the fea-fhore, it grew very 

 fhivery, argillaceous, and finally a true marl. The 

 xvhole country, from Rome to Civita Vecchia, is 

 flat, and feems to have been accumulated by ma- 

 rine alluvions. 



From Civita Vecchia to the alum quarries near 

 Folfa is eleven Italian miles, the road continually 

 afcending through woody countries, over the 

 following ftones. 



1 . Near Civita VeccUa, white, grey, and reddifh 

 marl-flate. 



2. White-grey limeftone. 



3. Blue, grey, or perlaceous marl-flate. 



4. Again limeftone. 



5. An argillaceous, either black, grey, or blue- 

 grey flate, in fome parts penetrated with iron, whence 



? I LI 1 J L J 



it was become black and hard. 



s- xT7i J j-rt ?Jil . 



6. White or reddifh compact marl, more or 



i f 1 j r 11 



lefs calcareous ; and, finally, 



_. . ... . ... , . . -i^qqo'j - 



7. White, high, and argillaceous hills, compact, 



with fcarce any vifible horizontal beddinas. Thefe 



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rocks yield the Roman alum. 



T , ' i i , , 



Hence it appears, that the whole country from 



Civita Vecctia to Volf* is generally calcareous, 



only 



