GUMMING ON THE ISLE OF MAN. 329 



eastward towards Skillicore, beyond the limekilns, two others, situ- 

 ated upon that line of disturbance which runs from the Brough in 

 a direction S. 40° W. mag., and which is evidently connected with 

 the great fault at Coshnahawin. The beds here are greatly altered 

 and disturbed, especially along the eastern side of the fault, where 

 we have a mass brought up from below, which I have little doubt 

 is an altered Old red conglomerate. On account of its beautiful 

 colour, some attempts have been made to work this rock for marble, 

 but the quartz occurring in it appears to have been the cause 

 of the failure that was experienced. Proceeding still to the north- 

 east, we again cross a trap-dike running S. 15° W., and branching 

 much amongst the outcropping shales : one of these branches ap- 

 parently connects itself with the series of dikes intersecting the 

 Skillicore boss, which is perhaps the most distinct and lemarkable 

 of these appearances, in consequence of its being so intersected. It 

 will be seen that whilst we have here a dike running in a direction 

 generally parallel to the disturbance at Ronaldsway, it divides itself 

 nearly at the centre of the boss, and that those branches which run 

 at right angles to the line of fault, separate again into mere cracks 

 only partly filled with trap, and ultimately disappearing. From 

 this boss to Coshnahawin, the shore between high and low water 

 mark has a gentle dip inland, and is occupied by beds of limestone 

 and shale, which are broken up into rhomboidal blocks by cracks 

 running generally towards the south-west. The line of high-water is 

 formed by a continuous mass of the altered Old red conglomerate 

 which has been brought up very rapidly ; the limestones, which are 

 almost horizontal to the very edge of the fault, being there suddenly 

 broken off. 



A small bay is here formed apparently by a transverse disturbance, 

 which has completely shattered and confused the beds, and the 

 broken masses are so enveloped in sand and shingle as to preclude 

 examination. We have however two parallel cracks with slight 

 faults running nearly south-east on the north-eastern side of this little 

 bay, and the beds then rise rapidly to the edge of the great fault 

 in that direction, at the mouth of the Santon river. At this point 

 also is another boss, through the centre of which runs a crack or 

 chasm, and there is also a crack and fault on one side of it. It will 

 be seen that, advancing from the south-western extremity of Lang- 

 ness in a direction nearly north-east, we have been gradually ap- 

 proaching the point of principal disturbance, which seems to be 

 under the hill called the Brough, where the Old red conglomerate, 

 which appears at low-water at the mouth of the Santon river, con- 

 formably underlying the limestone of Coshnahawin Head, has ))een 

 brought up on the rise side of the fault to the height of 110 I'eet. 

 As far as I can judge at present, this elevation was however connected 

 with the formation of two faults crossing each other, and occurring 

 at different periods. The valley along which the Santon river runs 

 is one of elevation, running for the most part nearly north and south, 

 and at the mouth of the little stream the effects of another disturbing 

 force may be traced, running in a nearly transverse direction, or from 



