1922.] ati.OL'O&Y OF ALDERNEY. 129 



The lower beds are preserved in the Coque Lihou area 

 and an early, pebbly stage of the series is met in all three 

 areas; the lowest beds at Coque Lihou are comparable with 

 the Jersey Conglomerate which they have been correlated. 



The contained pebbles are mainly quartz, aplite, granite, 

 porphyry, rhyolite, quartzite, and rounded and broken fel- 

 spars either pink or white. The rhyolite resembles the con- 

 tained rhyolite of the Jersey Conglomerate, in that island a 

 local rock. The Conglomerats fiompres of the Cotentin also 

 contain it. 



The grits contain mainly pink felspars, and quartz. It 

 would not be difficult to locate the constituents, except the 

 rhyolite, in the rocks of Alderney. 



The grits of the north-east extend from Corblets Bay to 

 Longy Bay, a shore line of nearly two miles. The beds are 

 fairly accessible both in the shore reefs and inland. The 

 quarry of Mannez, the largest in the island, and Berry's 

 Quarry, are in this area. The base is not seen as the beds 

 are faulted down against granite in Corblets Bay. 



Mannez Quarry shows faulting, and there is another 

 fault at Hommet Herbe Fort. 



In Berry's Quarry are mainly pink and green variegated 

 beds, the alternations occurring in bands, six inches to ten 

 inches wide. There is considerable broken felspar. The 

 base» of this quarry is conglomeratic, containing rhyolite 

 pebbles one third of an inch in diameter. The vertical thick- 

 ness of the beds in this quarry is 210 feet. 



In Corblets Bay there is fine stratification with a sequence 

 of I 50 feet rising to Corblets Point. At the top of this point 

 lie the pink and green grits. Bands in both varieties show 

 false bedding . Pale grey grits underlie these, (4) of the 

 series. The west of the bay contains the granite of Bibette, 

 and the faulting here seems to be considerable. The junction 

 is obscured by shore sand and sand dunes. 



In Cat's Bay there is faulting, the down-throw westward, 

 and the same beds recur. The faulting at Hommet, Herbe 1 

 Point, gives an eastern down-throw, introducing higher beds. 

 South of this latter point are the grey-white grits, but as one 

 progresses down the sequence to Raz Island, the variegated 

 beds are met again below Grande Folie, where the major 

 fault trace, crossing the island, is met. 



In Mannez Quarry the grits cover a surface of a quarter 

 pi a mile. They are invaded in the east by a kersantite 

 dyke, ten feet wide, running N.N.W.-S.S.E., and in the 

 west by a dolerite dyke, twenty feet wide, running N.N.E.- 

 S.S.W., occupying a fault fissure. The Mannez Quarry 

 sequence contains three of the ten beds given, the miHdle of 



