Reviews — Noury's Geology of Jersey. 131 



P3n'omericles (perlitio felstones?), which in one locality named 

 pi-esent immense spherules attaining diameters of as much as a foot. 

 " Spherolithes " nearly as large are mentioned as occurring in 

 one of the diabase dykes, but the description points to these being 

 spheroidal weathering. The localities of mica-trap dykes are 

 carefully enumerated. 



The sedimentary rocks are said to be chlorite-schist (the first 

 notice of its occurrence in Jersey) ; felspathic schist or grit, includ- 

 ing by far the largest part; metamorphic schist; and conglomerate. 

 The metamorphic schist is divided into " spilites " and " porphyres 

 argilenx," the distinction made between these is not very clear. 

 The author seems to regard both as altered forms of the felspathic 

 schists, but alludes to the possibility of the " spilites " being 

 eruptive. The metamorphism he thinks mainly due to the eruption 

 of the porphyries ; he does not seem to have considered the 

 idea that they may be ashes belonging to those eruptions. The 

 remarkable conglomerate of the N.E. corner is very fully described. 



Next comes a chapter on "Contours and Relief of the Island," in 

 which its physical geology is treated with admirable completeness. 

 The caves and clefts, the giants-kettles, pits, and natural tunnels, 

 are enumerated and explained almost individually : similarly with 

 the inlets, clifi's, and bays. Specially interesting are his descriptions 

 of the Pinacle and the Creux de Vis or Trou du diable. The origin 

 of nearly every valley is discussed, and many valuable remarks are 

 made on the causes which guided and shaped the channels. 



In the chapter on the Past of Jersey the author assumes the 

 hypothesis of an original granitic crust on which afterwards the 

 gneisses were deposited in an intensely heated ocean. Sedimentation 

 in a more normal sea laid down the Jersey rocks which he calls 

 schists, and to which he assigns a Cambrian age. (The term 

 schist is not very appropriate to these rocks.) Nothing shows, he 

 says, whether the true granites are prior to them or not ; the other 

 eruptive rocks are certainly later, and range from Cambrian or 

 Silurian to Triassic ; evidence is to be found in other regions. No 

 sedimentary rock exists between the Cambi'ians above named and 

 the conglomerate ; to this he attributes a Permian age, and he gives 

 good reasons for regarding it as due to sea-wave, not torrent 

 action. A section on Quaternary and modern geology contains a 

 very able discussion of past oscillations of land and sea. After 

 a careful sifting of the evidence, he concludes that since the Eoman 

 occupation only subsidence has happened : and that probably 

 Jersey was still joined to Normandy as late as the sixth century. 

 The discussion of this question contains many interesting remarks 

 on dunes and their growth, submerged forests and their mode of 

 origin and destruction, the formation of raised beaches, and other 

 important points in littoral geology. He adduces reasons for thinking 

 that some at least of the " raised beaches " of the Channel Islands 

 are not due to changes of level. 



A vein of humour appears here and there : as in the relation of 

 a stonemason's belief that building-stones can be corroded by the 

 moon's rays. 



