168 Mr. Finch's Account of some Basaltic Columns [Sept. 



different species of trap from that which I had just procured ; 

 and on inquiring whence it came, I was directed to Pouck Hill, 

 where a quarry has been worked many years. This hill is 

 situated one mile and a half north west from Walsall, at a short 

 distance from Bentley Hall, which is noted in history as a place 

 of concealment for Charles II. The estate belongs to Viscount 

 Anson. On the north east it adjoins Birch-hill colliery, to which 

 the ground descends by a gentle slope, and at the bottom a 

 small stream of water forms a boundary between them. The 

 distance from one hill to the other does not exceed half a mile. 



By barometrical measurement, the highest part of the hill is 

 60 feet above the level of the colliery, and constitutes a part of 

 the formation of trap, noticed by Mr. Aikin as forming an 

 elevated ridge, which crosses that place. The basalt extends 

 without any interruption from one to the other. It is about 30 

 feet lower than Bentley Hill, which is the highest land in the 

 vicinity, and consists of gravel overlying the coal formation. 



The extent of the trap may be estimated at nearly a mile in 

 length. It varies extremely in breadth, from half a mile to 30 

 or 40 yards, which is the breadth at Birch-hill colliery. Pouck 

 Hill may be regarded as situated near its centre. The opening 

 of the quarry at this place has exposed to view some fine basaltic 

 columns ; many of them are four or five feet in diameter. After 

 their crystallization on this large scale, they appear to have been 

 subject to fissures, dividing them longitudinally ; but the original 

 hexagon can still be distinctly traced. Their length is various, 

 some of the articulations being very short, and others extending . 

 to five or six feet. The direction of some is singularly waved, 

 whilst others are straight ; and from their lying in an almost 

 horizontal position, they resemble at a distance the massy 

 trunks of trees piled one upon another. Some of the basalt has 

 attached to it a small incrustation of carbonate of lime in irre- 

 gular spots. The trap of which this hill is composed is exactly 

 similar to that of the Rowley Hills ; of which an account is given 

 by Dr. Thomson in the Annals of Philosophy for Sept. 1816. 

 Those hills are at the distance of 10 miles, and no connexion 

 can be traced between them. 



Near the summit of Pouck Hill is a farm house, to supply 

 which with water a well about 16 yards deep has been sunk in 

 the rock, the lowest pump tree resting on a basaltic column. 

 When the Birch-hill colliery was worked four years ago, the 

 steam engine, employed to keep the mine free from water, 

 drained this well, although at half a mile distance. The same 

 effect was lately produced by cutting a deep trench on the oppo- 

 site side of the hill beyond the boundary of the basalt. These 

 two circumstances seem to prove, that this basalt is a superin- 

 cumbent formation covering the coal. The stream already 

 mentioned as separating Pouck Hill from the colliery, has worn 

 itself a channel four feet deep ; here the coal strata rise within a 



