3 42 GEOLOGY OF THE BKISTOL COAL-FIELD. 



Dadoxylon approximatum ("Williams) 



Upper Coal MEAsufiEs. 



We now come to the highest and last portion of the Coal 

 Measures. Owing to their being so near the surface many of the 

 seams have been washed away. They may be examined at Coal- 

 pit Heath, Parkfield, Westerleigh, Radstock, and Parringdon. 



The Coalfrom the workable seams in Gloucestershire is of very good 

 quality, some being highly bituminous. They are well adapted for 

 gas and steam purpose?. 



From Brislington, southwards, the Coal measures are covered up 

 completely by the IS'ew Eed Marls, Lias, and inferior Oolite ; after 

 passing under Dundry Hill they emerge and come nearer the surface. 

 At Clandown the shaft commences at the junction of ^ inferior Oolite 

 with the Upper Lias, and reaches the '' Great " seam at the depth 

 of 1212 feet. At Radstock the beds of Coal are thin, and 

 necessitate the removal of an immense mass of useless shale. 



The Upper Coal Measures have a total thickness of 3000 feet, 

 and contain 22 workable seams of Coal with an aggregate thickness 

 of 18 feet. 



The Upper Coal Measures afford the most abundant supply of 

 fossil plants, especially ferns. They are obtained from the shales 

 overlying the Coal. 



The following are the depths from the surface, to which shafts 

 have to be sunk before reaching? the first workable seam of Coal. 



The ^faults are very numerous, and some of them very deep. 

 They penetrate in every direction, and in various ways. The strata 

 appear not only to have been severed by a down or up throw, but 



