Mr. Hvtton on the Stratiform Basalt. 187 



No. VI. — On the Stratiform Basalt associated with the Carboniferous 

 Formation of the North of England. By Wm. Hutton, F. G. S., &c. 



Read, December I9» 1831. 



A Bed of Basalt is well known to exist in the midst of the Mountain 

 Limestone group of the North of England, which is designated in 

 Alston Moor and the adjoining mining fields " the Whin Sill."* It 

 would now be a useless waste of time to set about proving the igneous 

 origin of this class of rocks occurring in the district under review, 

 Professor Sedgwick having set that question at rest in his account of 

 High Teesdale, published in the Transactions of the Cambridge Philo- 

 sophical Society. 



The nature and origin of this bed being thus so entirely different 

 from the rest of the formation in which it occurs, has naturally attached 

 to it a good deal of Geological interest, Basalt being generally found 

 breaking through and forcing itself into contact with rocks of every 

 age, producing upon them changes mechanical and chemical which 

 afford the most conclusive evidence of its being a stranger and in- 

 truder. 



The writer of the following observations having frequently visited 

 the Whin Sill in different parts, and lately made a pretty extensive ex- 

 amination of it, begs to submit to the Natural History Society, the 

 views he has been induced to entertain of its nature and connexion 

 with the surrounding strata. 



The general rise of the beds of the Carboniferous formation is in 

 Alston Moor, and the adjoining districts, towards the West, where it 

 terminates abruptly in a series of hills, of which Cross Fell is the 



* The word Sill, which is generally used in the Lead mine district of the North of Eng- 

 land, is synonymous with Stratum. 



