Mr. N. Wood on the Geology of Northumberland, ^c. 303 



the second class of strata as exhibited in this district, contrary to the 

 received opinion of Geologists, which it shall be my object to elucidate. 

 It is considered characteristic of the suite of rocks. No. 2, that the 

 great beds of Coal occur in the upper part of the series. Messrs. 

 CoNYBEARE and Phillips, in their work on the Geology of England and 

 Wales, speaking of this, state, " Although it is true, that in Northum- 

 berland traces of Coal occur near the bottom of the Limestone deposit, 

 still the general rule holds good there also, for the upper part of the 

 series, in that county, contains frequent and thick seams of Coal, and 

 in that part no Limestone is found : then after an interval of an inter- 

 mediate character, corresponding to the Millstone Grit and Shale forma- 

 tion of Derbyshire, containing Sandstone and Shale, with two or three 

 thin beds of Limestone and Coal, follows the great Limestone deposit, 

 containing eighteen beds, many of them of considerable thickness, se- 

 parated by Shale and Sandstone ; and, lastly, the old Red Sandstone. — 

 This part of the series contains only two thin and unworkable seams of 

 Coal ; for the Coal-beds which are found associated with Limestone in 

 the north of Northumberland, belong to the intermediate formation 

 between the Limestone and regular Coal Measures ; so that here there 

 is in fact no exception to the general rule ; for all the workable Coal is 

 above the great central Calcareous deposit, and below it are only im- 

 perfect traces of Coal, and those of the rarest occurrence." — Note, p. 

 312. 



In accordance with this view of the Geology of Northumberland we ' 

 find, on a reference to their Map, that the whole of the county, west of 

 a line from the Coquet to the Tweed, up to the base of the porphyritic 

 hills of the Cheviot, is denominated " Millstone Grit ;" and this for- 

 mation is made to stretch in a south-west direction, to the New Red 

 Sandstone deposit of Carlisle : while to the north it is made to surround 

 a patch of New Red Sandstone, forming the vale of the Tweed. The 

 great series of beds of the Mountain Limestone is, on the contrary, con- 

 fined to an almost insulated tract, south-west of a line from Morpeth to 

 Carlisle. 



The very useful Map of Greenough, exhibits nearly the same 



