i 



360 MINERALOGY OF THE REUHEADr. 



These appearances of the sandstone-conglome- 

 rate and gravelstone, seem to indicate the opera- 

 tion of a disturbing force, acting on the water, 

 from which these beds were deposited, but of its 

 nature or direction, we will probably forever re- 

 main ignorant. 



I have before mentioned, that the rocks of sand-' 

 stone extend from Aberbrothick to the flag- staff at 

 Ethie ; but to the north-east of the flag- staff, and 

 near to the ruins of St Murdoch's Chapel, these 

 rocks terminate, and are succeeded by beds of trap-, 

 which form the cUffs on the shore to Lunan Bay, 

 and towards Montrose. These rocks of trap, w^hich 

 are termed by the inhabitants scu7^die, possess none 

 of those perpendicular fissures which characterise 

 the cliffs of sandstone, and hence tovv^ards the sea, 

 they present a surface more irregular and broken. 

 The beds are of considerable thickness, some- 

 times upwards of ten feet, and at other places on- 

 ly a few inches. Although somewhat irregular, 

 yet th€ stratification can be distinctly traced, and 

 it corresponds exactly with the sandstone, both in 

 direction and dip. This is very distinctly dis- 

 played on the shore, where the line of junction is 

 visible ; and in the general direction of the rocks 

 inland, numerous quarries being opened in the 

 xocks of scurdie to obtain materials for repairing 



