82 Observations on Ihe Geology 



the day in mountainous countries. Analogy would then enable us 

 to discover them where they are not known at present." 



I visited the coal districts of NorthumI)erland and Durham in 

 the summer of 1 813, and had frequent, communications witli 

 several of the most intelligent coal proprietors and agents, and 

 with gentlemen who were interested in geological inquiries. 

 Much has been already done to elucidate the geology of ])art of 

 these districts by Mr. Westgarth Forster, whose section of tlie 

 strata taken in great part from actual admeasurement comprises 

 the coal districts on the eastern and middle parts, and the metalii- 

 ferous limestone districts on the west, an extent of forty miles, 

 and an actual depth of nearly 1400 yards. This section, per- 

 haj)S the most important and extensive that has ever been made, 

 was taken by a person educated as a practical miner, who had 

 spent the early part of his Ufe in that district ; as such I consider 

 it particularly valuable. It was published in 1809. I am a hf- 

 tle surprised it has escaped Dr. Thomson's notice when describ- 

 ing the geology of Northumberland and Durham. If the present 

 paper have no other merit than that of making Mr. Forster's 

 section more generally known, it will render an acceptable ser- 

 vice to English geologists, and do some justice to a person 

 whose labours have not been sufficiently appretiated. 



The mineralogical district to which the present observations 

 relate, is bounded by the river Tees and the Cleveland Hills on 

 the south, by the German Ocean on the east, by the porphyry and 

 amygdaloid of the Cheviot Hills on the north, and by the mountain 

 of slate porphyry, gray-wacke, and sienite of Cumberland, on the 

 west. The general arrangement of the strata in Northumberland 

 6iid Durham is such as prevails on the eastern side of England, 

 as represented in the map prefixed to my Introduction to Geo- 

 logy, namely, the upper calcareous strata with magnesian lime- 

 stone on the east, the strata containing coal range through the 

 middle part, and the metalliferous limestone districts rise to the 

 ^cst. The strata on this side of England generally dip towards 

 the east, and rise gradually towards the west or south-west, when 

 the descent becomes abrupt; which is also the case in Yorkshire, 

 Derbyshire, and the north part of Staffordshire. We may con- 

 sider this district as divided into three parts, consisting, 1st, of 

 calcareous strata with magnesian limestone ; 2dly, of the coal 

 strata ; and 3dly, of the lower metalliferous strata. 



The first, or magnesian limestone district, on the east, was not 

 described or measured by Mr. W. Forster, as it contains neither 

 metallic ores nor coal *. It presents, however, many features 

 particularly interesting to the mineralogist, of which I shall en- 



* This must be taken with some limitation, as we shall presently have 

 to observe. 



deavour 



