434 ON THE GEOLOGY OF THE 
fragments, and in caverns, in massive columns, we find a 
great deal of that stalactitic limestone known by the name of 
Antique alabaster, which is likewise found filling the rents, and 
forming the cement of the Brésche en place. The mode in 
which this substance has been infiltrated, is finely exemplified in 
the sections laid open in forming the new road above alluded to, 
where cavities occur, in some respects very much resembling 
those of calcedony, as seen in the trap rocks of Feroe, though on 
avery different scale. The calcareous matter has been deposited. 
gently and slowly on the sides of the hollow, here and there 
has fallen in stalactites from the summit, either disengaged in 
columns, or along the sides, and then forming horizontal plat- 
forms at the bottom, like the onyx in thousands of the pebbles 
which occur in the amygdaloid of Scotland. Connected with 
all these, however, is the vein by which the infiltration was in- 
troduced ; and in this lies the distinction between those calca- 
reous and the calcedonic geodes. 
Besides this species of cement, there are others, one of which 
forms a very compact limestone, and often presents an even con- 
choidal fracture, of a pale reddish-brown colour, and frequent- 
ly dendritic ; this passes into a coarser variety, with somewhat 
of a splintery fracture, and of a dark-red colour. There 
are some very remarkable examples of the infiltration of this 
material, where the great beds of limestone are not only as it 
were soldered together, but where, having been broken down 
into the smallest fragments, they are again consolidated, and 
form the most compact masses. . Another cement is of a pale 
brick-red colour, more earthy in its texture ; and when it forms 
the base of the white variety of limestone, it has a very beau- 
tiful and singular effect. The fragments are sometimes in very 
large masses, and sometimes in very minute particles. Where 
exposed to the action of the weather, the cement is frequently 
washed 
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