xi. GOAL. 495 



London basin is hypothetical, but not wholly to be rejected, because 

 movements of great length in the periods following the coal 

 measures, some running north and south and others east and west, 

 were seldom single, but usually marked by several ridges and 

 hollows, which on a great scale were rudely parallel. 



According to this general view, then, the modern basin of London, 

 or the southern part of it, may have beneath it from end to end 

 a disturbed, probably narrow, system of coal strata, the quality 

 of which may be conjectured, from its place between the Belgian 

 and Welsh strata, to be good. Is it accessible ? at what probable 

 depth ? 



Here we come upon the researches of Mr. Hull in respect of 

 the thickness of beds usually covering the coal. By his examination 

 it appears that the thickness of these beds, in a general sense, 

 grows less and less as we proceed to the eastward and south- 

 eastward from the midland coal-fields ; and this to an extent which 

 must be regarded as very important practically. The Permian 

 strata, in some places a thousand or more feet in thickness, are 

 in other parts not so much as a hundred. 



The new red deposits, which probably exceed 1000 yards in 

 Cheshire, and 500 yards in the country near Birmingham, are 

 thought to be not more than 200 yards thick in the vicinity of 

 Warwick and Stratford. The sections given in this work, PI. III. 

 and PI. IV., shew how greatly attenuated in the eastern direction are 

 the liassic and oolitic deposits. The lias, probably 1000 or 1200 

 feet thick in the Vale of Severn, dwindles to about 400 feet in 

 the Vale of the Cherwell; and the Bath oolites are reduced from 

 500 feet near Cheltenham to 100 feet in the country near Oxford. 

 It must follow from these data that coal measures, if they exist, 

 would not be situated at an inaccessible depth in the country north 

 of Oxford -, but there is no good reason for selecting that or any 

 other situation in the upper drainage of the Thames for an 

 experiment, excepting that there the upper oolites and chalk are 

 not to be encountered in the sinking. 



IRON. 



Three bands of iron-ore occur in the country round Oxford, 

 each rich enough to be worked for small spaces, neither so 

 continuously productive as at present to bear comparison with 



