ISLE OF MAN. GEOLOGY. LIMESTONE. 567 



assign causes for the changes in this place, of a nature 

 similar to those which have been supposed to have acted 

 in Sky, it can only be conjectured that the granite of the 

 Isle of Man exists beneath these strata, at a distance suffi- 

 ciently small to have produced the effects in question. 



It is enough to have suggested this hypothetical expla- 

 nation of an obscure and very interesting circumstance ; 

 but before entirely dismissing the subject, it will not be 

 useless to inquire how far the history of this limestone can 

 be applied to the illustration of other instances where the 

 same or similar obscurities exist. Of these I am prac- 

 tically acquainted with two only; the case occurring in 

 Sky, already sufficiently considered, and that of Plymouth. 

 The difficulty which occurs in respect to the characters 

 and connexions of the unstratified limestone of Plymouth, 

 arises, probably, in a great degree, from an insufficient 

 acquaintance with it. In its disposition and general cha- 

 racters, it strongly resembles the examples here described, 

 and, like the whole of the limestone of the Isle of Man, 

 it follows an argillaceous schist which is incumbent on 

 granite. It is probable that a closer investigation of its 

 connexions may hereafter enable us to draw the com- 

 parison still nearer, and to ascertain its resemblance in the 

 more important particulars still wanting to complete its 

 history. 



This suggestion will not be fruitless, if it shall stimu- 

 late those who may have an opportunity, to trace it with 

 the care and perseverance which it merits and requires. 

 To those who are inclined to undertake this pursuit, I 

 may point out the propriety of endeavouring in the first 

 place to trace its contact with the fundamental rocks ; 

 secondly, of searching for the stratified limestones which 

 may exist in the same district, and of comparing the 

 organic remains contained in each ; and lastly, of attempt- 

 ing to determine, at some intermediate points between the 

 two, whether the real transition of the unstratified into the 

 stratified rock cannot here also be found. 



