360 Geological Notes. 



surveyed this part of the country dissented from Dr Harkness's 

 opinion. I am not aware of the views of those gentlemen on the 

 subject, but, on my own account, I beg to differ from such an 

 •opinion, and will endeavour very shortly to state my reasons. 



The three ridges out of which the Craigs have been hewn are 

 masses of permian breccia, resting on sandstone — the sandstone 

 •of Georgetown and Craigs quarries. It is not a very material 

 point, but we may note the heights as given in the New Ordnance 

 ■sheet: Maidenbower Craig, 276.1 feet; Middle Craig, 247.4 

 feet; Lower Craig, 200 feet above sea level. The height from 

 the base of the Maidenbower and Middle Craigs, measured by the 

 ■eye, I take to be somewhere about 100 feet — standing up as sheer 

 perpendicular cliffs, and I dissent from the fault theory, because 

 (i) "faults " are not found in such form; (2) if the Craigs were 

 formed of two faults the dislocation would have shown in greater 

 length ; (3) at the Middle Craig, north side, the sandstone is 

 seen dipping below the breccia, which would not be in the case 

 of a fault ; (4) at Craigs Quarry, Maidenbower Craig, you can see 

 the thick-bedded sandstones with breccia on the top. This is 

 opposed to the existence of a fault. In my opinion, the Craigs 

 are simply the topmost of the series of regularly alternating beds 

 of sandstone and breccia with which the whole of the Dumfries 

 Basin is filled, as has been shown by the well borings mentioned 

 in a former paper. At the Gasworks the bore went through 

 twenty alternations of sandstone and breccia, and, having gone 

 •down six hundred feet, had not reached the bottom of the strata. 

 There cannot be a doubt, I venture to think, but that the appear- 

 ance of these cliffs is due to the action of the waves and breakers 

 ■of an ancient sea. The mechanical force exerted by storm-driven 

 waves on a rocky shore is, as is well known, very great. It 

 IS a force always in action, and with the rise and fall of the tide, 

 four times a day, it acts like a saw, cutting horizontally into the 

 land ; not so much from the weight of the waves alone as from the 

 enormous power which they exert in times of storms and great 

 ■gales, pushing forward great masses of gravel, sand, boulders, 

 and dislodged masses of the rocks against which the waves are 

 ieating, and so pounding and battering the opposing barrier, until 

 in process of time, in the case of a very hard rock, vertical cliffs 

 are sculptured out of the line of coast. Such is the process by 

 which I venture to think the Craigs have been formed. As to 



