52 On certain Points connected with. 



and iron stone ineasures, reckoning downwards, in some 

 places, as in the Forest of Dean, the iowest coal is only se- 

 parated from it by a few inches of clay. 



The measures which rest upon the third limestone, I de- 

 nominate the upper coal series: the boldest feature in this 

 asseiiil)lae:e is a gray greenish micaceous sandstone, measur- 

 ing m thickness fully 200 yards ; this forms uncommonly 

 bold high land, from Myrthr Tidvil to Caerphilly, along 

 a considerable extent of the South Wales coast, and in the 

 Forest of Dean, fine plains wiih rounded edges, from 7 to 

 800 leet above the level of the sea. In Wales it is called 

 the Gray Rocks, and the Pennard Rock in the neighbourhood 

 of Bristol. 



Between this and the Farev\cll Rock are contained the 

 iron-making coals and ironstone of the South Wales Bason, 

 the former of which, according to Mr. Martin, amounts 

 to 95 feet of workal)ie coal. I have not seen any state- 

 ment, nor have I heard of any coal being worked in South 

 Wales at any great height in this series above the Gray 

 Rock. Should this prove the case, the Forest of Dean 

 supplies the void that would otherwise have been occasioned 

 in the general section, as it contains from 3 to 400 yards of 

 coal measures, occupying a higher range in the series, and 

 inimediatelv above the great Gray or Pciniard Rock. These 

 measures are composed of twelve s.-ams of coal, and are 

 surmounted by a considerable thickness of a straw-ciiloured 

 sandstone, coutaining occasionally beds of red marl. From 

 this circum!?tance, and from the absence of red cround 

 upon the surface of the coal measures in the Forest of Dean, 

 and in South Wales, as far as I have seen, I am induced 

 to think that this sandstone, containing the red marl, where 

 there is cover, is overlaid by the upper Somersetshire coals, 

 and these again, by cliffe or shale, on which rest the upper 

 red, v\hich I conceive to be a species of red calcareous rnarl. 

 Suliject to this arrangement, we find that the upper series is 

 formed into three distinct divisions wit!i red marl above, 

 and the great red (from under the third limestone below) ; 

 the whole thickness, of which series may be estimated at 

 ISOOvards. 



Having: thus, according to my observation, supplied the 

 chasm complained of by my friend Mr. Farev, f shall shortly 

 su'tjoin an outline of what I believe to be the general order 

 of the British strata. 



London clays and sands reaching to the chalk: 



Measures from the chalk to the third or great oelite, com- 

 prising the green sand^ Bedford sand, 1st oelite or 



Poiiland 



