64 
between high and low water mark, where it is about 50 
feet thick, and perfectly conformable to the limestone. (Plate 
III. B.) Its junction with the silurian can be seen in many 
places ; perhaps the most striking is a natural arch, the lower 
part of which is silurian and the upper conglomerate, the 
conglomerate being intersected by a dyke.* (Plate III. C.) 
At Peel, the red beds are, almost entirely, the fine-grained 
thick-bedded sandstone of which the town is built. They 
form the cliffs for a distance of about two miles 1*^^. from Peel. 
The Hev. J. Gr. Cummingf has estimated its thickness at 300 
feet, and has pointed out the fact that although there is no lime- 
stone on it now, beds of limestone, probably carboniferous, 
were removed from it some years ago for burning, and the 
shore is strewn with limestone blocks, probably washed up by 
the sea from beds still existing. 
Having now touched upon the various localities in which 
these red beds are found, it remains to consider the mode of 
their formation, and their position in the geological series. 
They are unconformable to the upper silurian, and pass 
upwards into the carboniferous limestone. They are, there- 
fore, certainly not older than the upper old red. They are 
composed of coarse materials, and bear other evidences of 
rapid accumulation, and in many places pass by regular 
gradations of colour and mineral character into the carbon- 
iferous limestone. 
Again, they rest upon an irregularly denuded surface of 
silurian rocks of all ages. jSi ear Shap Fell they lie nearly 
horizontally upon the upturned edges of the elevated rocks. 
* The dyke is the cause of the arch. Being more readily decomposed 
than either the schist or the conglomerate, the sea washed through, and then 
enlarged the hole to its present dimensions. On the other side of Langness, 
the decomposition of trap dykes which intersect the schists, has caused many 
long narrow inlets of the sea to be formed. 
+ " On the Geology of the Isle of Man." Quart. .Journ., 1846. 
