Kotes on the Geology of Bray Head. 331 



quartz reef appears much thicker than it is in reality, as it is 

 crossed by a break, by ^hich it is doubled upon itself. Turning 

 somewhat towards the south it becomes less compact on its 

 under side ; but the sequence south of this is indistinct, as 

 the ground is much broken. On the north or upper side it is 

 overlaid by grits and slates that are quite conformable to it. 

 However, on looking up the slope of the hill, these appear to 

 strike away from the quartz reef, which forms a very conspicuous 

 feature right across the summit of the hill. South-east of this 

 ridge there is a marked hollow across the hill, on the opposite 

 side of which, in the lands of Ballynamuddagh, numerous small 

 masses of quartz rock appear, which seem to represent one band 

 of quartz rock much twisted and broken. This to the west disap- 

 pears under the drift, while to the east it is cut off by a series of 

 N.W. and S.E. breaks. 



Still further south there is the second reef* (E.E'), forming a 

 conspicuous ridge, and the highest point on the hill (793 feet). 

 It extends from the Brandy Hole along the bounds of Ballyna- 

 muddagh and Rathdown Upper, towards Windgate. Like the 

 main reef (B.B') further north, it is much broken up by faults.- 

 In the section as seen on the shore it is overlaid by grits and 

 slates having a reddish burnt appearance. The under surface of 

 the reef has several peculiar rounded masses projecting from it, 

 and rests on a comparatively soft, reddish sandy bed, under 

 which are slates and hard quartzose grits. Some distance below 

 these a bed of greenstone appears in the cliffs and railway cut- 

 ting, and can be traced up the steep slope of the hill for some 

 distance, but is lost under the drift towards the top, and could 

 not be found further to the west. 



The grits and slates on this southern slope are much twisted 

 and folded, being repeated many times, as may be seen along the 

 shore and railway cuttings (Plate XXV.), especially at the most 

 southerly point of the head, beyond which, towards Greystones 

 and towards the west, they pass under a deep covering of drift 

 that extends tor some distance up the slopes of the hill. 



* The surfaces of these reefs are in many places well glaciated. The stria being well 

 preserved on the quartz rock, numerous other glacial evidences are to be found over the 

 hill, such as transported blocks. The projecting headlands along the shore-line are also 

 striated in some cases on highly-inclined or vertical faces. 



