Mitieralogy of Sky, 39 



mouth, and as yet Involved in so much obscurity, may perhaps be- 

 long, and w^hich have been ranked in the class called transition by 

 the Germans, since they were supposed to be of higher antiquity 

 than the secondary or Jioetz strata of the same school. This bed is 

 found at Loch Elshort immediately following the sandstone, with 

 a common dip, and in every respect perfectly conformable to it. 

 It is readily distinguished wherever it occurs, provided its upper 

 surface be exposed to the weather, and this at very considerable 

 distances, the appearance which it here puts on being that of detached 

 and irregular masses with a deeply honey-combed surface, the 

 cavities being from a foot to two in depth, rounded and perpen- 

 dicular, while the projecting portions are equally rounded and 

 smooth. No lichen attaches itself to that surface, but whatever its 

 hue be. It weathers to a bluish colour, by which it Is visible among 

 all the surrounding rocks. I could find no means of ascertaining 

 its thickness at Loch Elshort, but near Kilbride where it Is fairly 

 exposed It Is some hundreds of feet thick ; I have however reason 

 to imagine that this dimension is very variable. It may be traced 

 where it first appears at Loch Elshort from the point where it Is 

 in contact with the sandstone, for a considerable way up the hills in 

 the direction of Broadford, but is at length lost amidst trap and 

 syenite, and amongst the mossy and deep soil of this rough ground. 

 Pursuing the line of shore it shortly disappears, other beds coming 

 in the way which will follow next in the order of descrip- 

 tion; but it is recovered at Kilbride, and hence may be traced 

 through the remainder of its connections to the no small surprise 

 of the geologist. As the sandstone bed does not exist at Kilbride 

 the identity of the limestone cannot here be proved by that of the 

 beds on which it reposes ; instead of sandstone indeed its lower 

 surface is found in contact with the syenite already generally 



