232 RETROSPECT. 



dominates, and felspar is entirely or almost entirely absent ; the 

 allied chloritic and talcose schists are characterized by a general 

 green colour and a softer consistency. In some places the tal- 

 cose schists are worked for making pots and stoves. The am- 

 phibolic masses, which occur chiefly on the southern slope of the 

 Alps, are distinguished by the presence of the black variety of 

 amphibole. In some places serpentine and gabbro* also occur, 

 which have formed a part of the mountains of the Valais, of Uri, 

 and of the Grisons. These rocks contain no traces of fossils; 

 so that they are destitute of any indications of organic life ; and 

 hence they have not improperly been denominated Primary 

 Rocks. They have prepared the ground on which living crea- 

 tures were in after times to appear. 



Crystalline rocks form the highest Swiss mountains, and con- 

 stitute the nucleus of the central Alps, on which are grouped to 

 the north and south the deposits of the Jurassic, Cretaceous, 

 Eocene, and Miocene periods. Even in the Miocene basin of 

 Switzerland, if we could penetrate to great depths, these older 

 rocks would be reached. In northern Switzerland they reappear 

 near Laufenbourg. The gneiss of Laufenbourg is connected 

 with the crystalline rock -masses of the Black Forest, which are 

 surrounded by a zone of Triassic and Jurassic rocks, consisting 

 in some places on their edges of a conglomerate manifestly pro- 

 duced by the weathering of gneiss. 



In Switzerland the anthracite-shales are found lying over the 

 crystalline rocks, and must therefore be regarded as the most 

 ancient fossiliferous formations which have yet been discovered 

 in that country. But from the geological constitution of other 

 countries it is known that a long period elapsed before the for- 

 mation of the Carboniferous rocks ; and the earlier strata have 

 been principally observed in Germany, Bohemia, Russia, Sweden, 

 England, and North America ; and they are divided into four 

 sections, namely the Laurentian f, Cambrian, Silurian, and De- 



* [Saussurite (tough Jade) constitutes gabbro rocks (Greg and Lettsom's 

 Mineralogy, p. 114). EDITOR.] 



f [An account of the Laureutian system is given in Sir Willian Logan's 

 1 Report of the Canadian Geological survey,' 1863 (chapter iii.), in which the 

 Laurentian strata are described as " altered to a highly crystalline condition, 



