86 Notices of Memoirs — Prof. Liveing on Metaniorjjhism. 



This is about all that conjecture at present can arrive at. There 

 "would seem indeed to be little hope of determining the question as 

 to the age of the rocks from a study of the island alone, or of all 

 the Channel Islands together by themselves. It can only be by 

 comparison of their geology with that of the neighbouring parts of 

 the Continent — of Normandy and Brittany — that we can expect a 

 solution of the problem. 



In addition to the syenites, and the sedimentary and porphyritic 

 rocks above described, there is a very important accumulation of 

 volcanic rocks (trap, porphyry, and amygdaloid), in the immediate 

 neighbourhood of St. Helier's, and which does not seem to have 

 been noticed either by Dr. MacCuUoch or Prof. Ansted. Com- 

 mencing at Gallows Hill, on the west of the town, the series may 

 be traced for about two miles northward, across both branches of 

 the Val des Vaux, to near the Grand Val Mill. It occurs again 

 between the two houses called the Hermitage and Bagatelle, 

 in the quarry east of Victoria College, and at the foot of St. Saviour's 

 Hill. It may be well seen in the quarries at the bottom of Gallows 

 Hill, and on the road up the western branch of the Val des Vaux, 

 where the focus of the eruption seems to have been. There is 

 nothing to indicate the age of these rocks except the alteration of 

 the shale (e) in their neighbourhood (as, e.g., on the Trinity Road, 

 and other places) into a claystone porphyry, proving them to be 

 more recent than it. The mention of this altered rock leads to 

 another and final question ; namely, what is the cause of metamor- 

 phism in the various rocks of Jersey ? It is not the syenite : for 

 at, or close to, its jimction with the shale (as, e.g., on the ascent by 

 the path from St. Aubin's into the St. Brelade's Road), the latter is 

 quite unaffected. 



The volcanic rocks may account for the alteration of the shale (e) 

 into claystone-porphyry ; but they do not account for the felstone 

 and hornstone-porphyries (/), which exhibit the same character, 

 both in the immediate neighbourhood of the trap (e.g. in the quarry 

 N". of Grand Val Mill), and miles away from it {e.g. at La Crete 

 Point, in Blanche Pierre Quarry and in Bonuenuit Bay). These 

 would seem to be porphyries belonging properly to the sandstone 

 series (/), but whether contemporaneous or intrusive I am unable 

 to say. Here again the study of the geology of Normandy and 

 Bi'ittany is essential to the understanding of that of Jersey and the 

 other Channel Islands. 



jsroTiOES o:f nvns3VLOiE.s. 



On the Metabiorphism of the Rocks of the Channel Islands, 

 By Prof. Liveing, etc., etc. 



A PAPER was recently communicated to the Cambridge Philo- 

 sophical Society (Oct. 29th, 1877) by Prof. Liveing, in which 

 the author traced the connexion of the rocks in Guernsey, and 

 pointed out the extreme variations in the amount of change these 

 rocks and some of those in the other islands had undergone, from 



