in the Neighbourhood of Edinburgh. 45 
granted that any such elevation as that here supposed has taken 
place, there seems to be every reason for ascribing this cause to 
that epoch. 
Several years have now elapsed since this interesting section 
was first laid open, and the public are indebted for the preserva- 
tion of so instructive a record of the changes and revolutions 
which have given rise to the present state of the earth, to the 
consent of the Magistrates of the City then in office, obtained 
through the active exertions of the distinguished Professor of 
Natural History in this University, and of his excellent friend 
the late much lamented Treasurer of this Society, Mr Tuomas 
Auxan of Lauriston, whose whole life was spent in the cultiva- 
tion of science and in contributing to its advancement. 
Postscript.—Since the foregoing pages were written, Mr 
Maceriuivray, of the Royal College of Surgeons, has very oblig- 
ingly put into the hands of the author, a sketch of the section of 
the Castle Hill, made by him when it was first laid open in 1829, 
from which it appears that a mass of trap was then exposed to 
view, lying beneath the disturbed strata. This igneous rock was 
so soon covered up in making the road, that it escaped general 
notice. It is described, however, by Mr Maceriiivray as being 
totally different, both in appearance and character, from that up- 
on which the Castle is situated, and more nearly resembling the 
dyke that was met with in excavating for the foundation of the 
9 
Cowgate Bridge. 2 
