Roiiie mid Victoria. 155 



south-west of the Portland Bay promontory. The period of 

 its occurrence was a modern one, being subsequent to the 

 limestone, our Tertiary stratum. 



" It is certain that, from whatever cause originating, a con- 

 siderable portion of the limestone upper crust was removed 

 when lying beneath the water, as we found part of that space 

 now filled with alternating sands and clay for fifty yards in 

 depth, on the north-eastern side of Lawrence. Subsequently, 

 then, to this deposition, itself so recent, was the submarine 

 eruption of which we were speaking. 



" As ashes rose from the vent and fell again into the waters, 

 they would float on towards the limestone rocks, and in the 

 waters of that shallow sea many of the pieces would gradu- 

 ally sink, and be mingled with the shifting sands. The 

 absence of much abrasion would indicate comparatively quiet 

 settlement. From the depth of stratum of the Conglome- 

 rate, it is probable that some little time elapsed dining which 

 fresh and continually occurring discharges from the sub- 

 marine crater provided new material. 



" There must have been some protection from the cuiTcnts 

 in the shape of projecting headlands, now washed away, else 

 so frail a substance would have been swept away before con- 

 solidation. It is clear that no great time was allowed for 

 the process, as we find no deposition upon the conglomerate. 

 It is then in the highest degree probable that the whole 

 coast line of the west rose almost immediately after such 

 cinder subsiding ; and it is equally probable that the last 

 throes of aU the volcanoes alluded to, were the agent of such 

 elevation." 



LAVA. 



Though tufa is the principal volcanic product of Rome, yet 

 lava, in its various forms, proceeded from even the modern 

 craters. One sees it there under romantic associations. The 

 castellated tomb of Ccecilia Metella, wife of Crassus, seventy 

 feet in diameter, was built outside the walls of Rome on the 

 very extremity of a bed of lava from Mount Albano. 

 Streams are here and there met with on the Campagna. 

 Not far fr'om the wonderfril St. Paul's Church, beyond the 

 walls, I saw the quarries of the street potygonal blocks, 

 the uncomfortable pathways of the city. The huge masses 

 of lava forming the highways of the ancient Romans, are in 

 most cases buried beneath the accimiulated rubbish of ages. 



