206 Mr. Warbuuton on Mag ne si an Breccia. 



magnesian limestone lies over the coal measures ; it is doubtful how- 

 ever whether the coal measures are conformable with the strata of 

 the magnesian limestone ; and it is not improbable that they lie 

 under it, having the edges of their tilted and broken sills abutting 

 against the lower surface of the superincumbent rock. 



The red marl is so widely distributed in that part of England 

 which lies between Lancashire and the southern coast of Devonshire, 

 and is so frequently found in that district in the same geological 

 position which it occupies in the northern and midland counties in 

 alliance with the magnesian limestone (lying for instance in horizontal 

 strata upon the inclined coal measures, and bounding them at their 

 basset) that it might be expected in some part of its course to dis- 

 cover traces of the magnesian rock. Accordingly I shall mention 

 some instances of the occurrence of a magnesian limestone in the 

 district above referred to, where it either alternates with red marl, or 

 may be considered as connected with it. 



In the course of a valuable paper on the Rocks in the vicinity of 

 Bristol, which was long ago presented to this Society, the author, 

 Mr. Bright, has given an account of the strata of red marl which lie 

 along the banks of the Avon. The red marl is there found either 

 lying upon the coal measures, or filling up the vallies that are occa- 

 sioned by the breaking off of the inclined strata of limestone, where 

 instead of the series of inclined strata that should rise from beneath 

 the limestone, horizontal strata of red marl are found resting upon 

 the broken edges of the limestone or of the first of the rocks beneath 

 it. It is in the red marl last described, as it occurs near Hung-road 

 on the Avon, that Mr. Bright discovered a limestone breccia, of 

 which there are two beds alternating with red marl. 



Having examined this breccia on the spot, after having consulted 

 Mr. Bright's paper, and having seen some breccias from the Mendip 



