Mr. Hutton on the Stratiform Basalt. 205 



aggregate thickness is 78 fathoms, 11 of which beds, upon the whole 30 

 fathoms thick, are above the Whin Sill. On the Gelt, from the first 

 visible bed of the series, which must be considerably above the Old Red 

 Sandstone up to the Coal Seam worked on Tindle Fell, which is some 

 distance below the Whin Sill (there a well known bed), we have, in a 

 space of 305 fathoms, no less than 24 beds of Limestone, whose aggre- 

 gate thickness is upwards of 95 fathoms. This view of the wedging 

 in and dilatation of the strata as we proceed northwards is further con- 

 firmed by the number and thickness of the beds, which rising to the 

 surface, present their edges between the Whin Sill at Sewing Shields, 

 and the transition rocks of Carter Fell, upon which the formation re- 

 poses. There are many well known instances of the " putting in" and 

 thickening of strata in the Coal field, and Mr. Buddle, in his valuable 

 Sections published in the Transactions of the Natural History Society 

 of Newcastle, has shown several ; one of the most remarkable is men- 

 tioned at page 201, where a bed of Sandstone, twenty fathoms thick, 

 is traced thinning out until it becomes a Stone-band in the Bensham 

 Coal Seam in Wallsend Colliery, and is known finally to disappear. 



The most curious subject of investigation connected with the Whin 

 Sill is that of its age in relation to the group of rocks in the midst of 

 which it is found. Professor Sedgwick, after his examination of it in 

 High Teesdale, comes to.the conclusion, " that the Whin Sill has been 

 produced by a lateral injection of volcanic matter in a state of igneous 

 fusion," and that this injection took place " posterior to the deposition 

 of the members of the metalliferous formation with which it is in contact." 

 From the connexion of the Basaltic rocks of the district he examined, 

 with certain Dykes which traverse the Coal Field, " he further con- 

 cludes, that " these Rocks must have existed in their present form be- 

 fore the deposition of the Magnesian Limestone," and that they " pro- 

 bably have been injected among the metalliferous strata, after the 

 deposition of at least a part of the Coal formation." I confess it is 

 with great reluctance I differ from such authority, but from my own 

 examination I am induced to come to different conclusions. To the 

 idea of its being a lateral injection after the deposition of the metalliferous 



