SIR JAMES HALL on the Consolidation of the Strata. 319 



ment, so as to be able to produce it with confidence to the 

 public. 



It may be interesting, in the first place, to describe, in a ge- 

 neral way, the geological structure of the country, in the neigh- 

 bourhood of the singular scene which gave rise to these specula- 

 tions, 



On different occasions I have laid before this Society obser- 

 vations made on the rugged shore which occupies the southern 

 entrance of our estuary the Firth of Forth, which, from being 

 frequently washed by a very boisterous ocean, presents to view a 

 distinct exhibition of its internal structure. The eastern part is 

 occupied by the promontory of Fastcastle, composed entirely of 

 the elder quality of strata, called by the Germans Grey Wacke. 

 Further to the west it consists of cliffs formed of Sandstone, 

 nearly in a horizontal position. These two meeting in the crag 

 called the Siccar Point, afford the most distinct view we any 

 where have of the peculiar relation and mutual history of these 

 two rocks. 



More inland, on the borders of Lammermuir, a set of hori- 

 zontal beds occur, consisting of a loose assemblage of rounded 

 stones, intermixed with sand and gravel, which bear every ap- 

 pearance of having been deposited by water, and which, as to 

 their general history, seem to have undergone no change since 

 the overwhelming, though transient, agitations of water, of which 

 I have frequently had occasion to speak in this Society. 



In the summer of 1812, as I was returning from visiting the 

 granitic range which occurs in the water of Fasnet, in the hills 

 of Lammermuir, and riding down the little valley of Aikengaw, 

 which deeply indents this loose collection of gravel and shingle, 

 about two miles above the village of Oldhamstocks, and at the 

 distance of eight or ten miles from the sea, I was struck with 

 astonishment on seeing one of these gravel banks, formed, as 



VOL. x. P. ii. s s 



