the Super-position of the Strata of England. 51 



the fact were established by other circumstances, since the 

 whole of the great red, and frequently the third limestone 

 series above it, forms deep red soil, in which gypsum is 

 frequently found. 



Ascending the series, the great red may universally be 

 considered as the next stratum in the order, and one of its 

 most distinguishing characters is the plum-pudding-stone, 

 or breccia, which occupies a superior situation in the mass, 

 forming bold edges, and stretching into table land, where 

 the stratification has become more horizontal. It is an 

 opinion not unfrequcntly advanced by geologists, that frag- 

 ments of breccia are a certain indication of an approach to 

 a primitive country. I should rather infer, that such frag- 

 ments betokened an approach to the upper beds of the 

 great red. What gives considerable strength to the former 

 opinion is the fact of the most mountainous districts, hi- 

 therto considered primitive, being contained in the superli- 

 cies occupied by this grand boundary to our two great coal 

 series. How different is the fact where elevation of surface 

 continues ! On these extensive plains of breccia, where 

 the measures are fairly extended, rests the third, or great 

 Jnncstone series. This is the limestone which underlays the 

 Staffordshire, Shropshire, South Wales, and Forest of 

 Dean coals. It is also the same as the Bristol limestone, 

 which is seen on the banks of the Avon, rising rapidly from 

 under ihe coal measures. This rock is also various in its 

 thickness : in the Forest of Dean I estimate it at 200 yards, 

 and from the enlarged dimensions of its beds on the west 

 side of the great Welsh bason, its thickness must be from 

 •■250 to 300 yards. 



Immediately upon this rock rests from forty to sixty yards 

 of what by many would be termed alluvial sandstone. It 

 is easily distinguishable from every other sandstone by its 

 pure siliceous base. It also contains from 15 to 20 yards of 

 breccia in solid stratified blocks, and several veins of the 

 same, In a more disintegrat.ed stale, which open and shut 

 in the same way as metallic veins. How irreconcileable to 

 these facts r.re the opinions of those who determine the 

 class of the stratinu, whether it be alluvial or not, by the 

 absence or presence of a single pebble I* These regularly 

 stratified beds of breccia, and veins of the same, rest under 

 more than 30 veins of coal, and nearly two perpendicular 

 miles of higher strata. The upper bod of this peculiar sand- 

 stone series partakes in soidc places of the nature of lime- 

 stone, and abounds with vegetable im|)ressions. In Wales 

 it is called the Farewell Rock, because it terminates the coal 

 D 2 and 



