Scientific hiteUigence. — GeoU^y. 199 



to find it formed of a pile of petrified matter, eighteen or twenty 

 feet in height by about forty in length, entirely composed at the 

 lower part of tlie petrified trunks of very large trees, lying 

 obliquely forward and outward ; above which the whole rock 

 consisted of petrified branches and typolithic leaves, intermixed 

 in various places with volcanic sand and gravel. Some of the 

 branches that lay in contact with the volcanic matter had a sco- 

 rified appearance ; the ligneous fibre is entirely consumed_, but 

 its texture is perfectly preserved. My surprise and joy at such 

 a discovery, to which I believe I may lay claim, was not lessen- 

 ed by finding this fossil forest to extend up the Via Flaminia to- 

 wards the Ponte Molle, forming, in fact, the entire range of 

 precipitous high ground to the right of the road, now full forty 

 feet in thickness. Before getting to the bridge it branches off 

 still more to the right, and about a mile above it there is an in- 

 terruption of this subterranean forest, where you perceive, un- 

 der the petrifactions, the original aqueous formation of the coun- 

 try, consisting of cemented gravel, sand, and clay, before it was 

 covered over by the volcanic dust, and the forest we have been 

 describing. A quarter of a mile higher up the Tiber you come 

 to a mineral spring, having a somewhat acid taste, which is fre- 

 quented for its medicinal qualities. The petrified forest now 

 crosses the Tiber, and you perceive detached parts of it ascend- 

 ing in the direction of the stream. The question naturally arises 

 in the mind, What could have occasioned so singular a catas- 

 trophe .? Is this the work of an earthquake, when this part of 

 the country was the scene of the volcanic convulsions, which so 

 many concomitant appearances confirm .? The gigantic nature 

 and extent of the phenomenon admit the probability of the con- 

 jecture ; the admixture of volcanic dust among the trunks and 

 branches of the forest strengthens the supposition ; the over- 

 thrown position of the whole mass shews that the event was si- 

 multaneous ; and the scorched impressions on the petrifactions 

 point out the agency of fire. The petrifacient matter is calca- 

 reous, but of a peculiar nature, different from any I ever saw 

 before. It is of a light brown colour, and very pulverulent. 

 The upper parts of the petrifactions partake of the friable na- 

 ture of the petrifacient, but, as it gets deeper, it becomes more 

 and more indurated by the increase of the superincumbent pres- 



