66 Dr Daubeny on the Columnar Structure of Tra'p-Rochs. 
tending to a considerable height on the opposite side of the 
valley from that whence it was derived. 
Instead, therefore, of conceiving that water caused a regular 
arrangement ^ among the particles of the lava, in consequence 
of the suddenness with which it cooled them, does not the pre- 
sent case lead us to the supposition, that the natural structure 
of the stone has been in this, and probably in other instances, 
developed by the continued action of the stream, which, in the 
course of ages, has cut itself a passage through the resisting 
materials of the rock. 
Do we not indeed generally observe the most beautiful ex- 
amples of columnar trap in rocks, which are either at present 
exposed to the action of water, or which may, without violence, 
be supposed to have been formerly in that predicament ? 
It is somewhat rare, I believe, to meet with any well marked 
instance of columnar trap in the interior of a mine "[* ; and if 
the occurrence of these pillars high up on the sides of inland 
valleys be brought forward as an exception, it should be recol- 
lected, that these very valleys have probably been themselves 
formed by the agency of water. 
At the same time, I am far from contending that the struc- 
ture which we observe in basalt is uniformly attributable to the 
above cause ; or, in other words, that the arrangement natural 
• I have carefully avoided the use of the word “ crystal,” with reference to 
the structure existing in trap-rocks, because I am aware that the term might be 
objected to, as being, strictly speaking, inapplicable to these columnar concretions, 
in which there is neither a definite number of planes, nor planes meeting at de- 
terminate angles. At the same time, when we consider the many points of ana- 
logy, it may not be too rash to assume, that the formation of crystals in simple^ 
and of distinct concretions in compound minerals, both probably depend Upon the 
same ultimate law of matter. Thus, Count Bournon, in his “ Traite de Chaux 
carbonatee,” p, 162., considers the fibrous and lamellated structure of that mine- 
ral a kind of irregular crystallisation. 
-f- Professor Buckland, to whom I shewed this paragraph, referred me to M. 
Faujas St Fond’s description of the Quarries at Nidermennig, near Bonn, for an 
instance of columnar lava at a considerable depth below the earth’s surface. I 
have since been at the spot myself, and found the columns extremely irregular, as 
indeed may be seen in M. Faujas’s plate, in the Annales du Mus, vol. i. Their 
appearance, indeed, is so different from that of the basalt of the Vivarais or the 
Giant’s Causeway, that the case seems hardly to bear upon the question, so far as 
it respects the latter. 
