Bibliographical Notices. 261 



(2) A second group of lakes has "been produced as a consequence of 

 compressions which have thrown the rocks into parallel folds on a 

 smaller scale ; when these are closed by tilting, so as to have no 

 outlet for the drainage, fiord-like lakes, such as those on the west 

 coast of Scotland and elsewhere, are the result. (3) A third group 

 is also exemplified by some in Scotland, where the waters lie along 

 anticlinal folds or saddles. (4) The fourth group of lakes comprises 

 those which have been excavated by ice ; some are dammed up at 

 their lower end, but others lie in depressions excavated in the solid 

 rock. Several of the lakes of Cumberland, he says, are susceptible 

 of explanation in this way. A very neat woodcut representing 

 Grasmere adorns this page, whence we may suppose that Professor 

 Seeley regards this lake as a case in point. But no allusion is 

 made in the text to the figure, and this practice obtains occasion- 

 ally throughout the book. 



A very large portion of the manual is devoted to volcanic pheno- 

 mena. After a sketch of the nature and origin of volcanic energy, 

 the author records the manifestations of volcanic action, and then 

 he plunges once more headlong into the rocks. Chapter XIV. 

 Nature and Origin of Igneous Rocks. Chap. XV. The Granitic 

 or Plutonic Group of Eocks. Chap. XVI. History of British Plu- 

 tonic Becks. Chap. XVII. The History of Volcanic Bocks. By no 

 means the least interesting chapter in the book is that devoted to 

 the history of volcanic activity in Britain. The literature of this 

 subject, one may say, is peculiarly the growth of the last twenty 

 years or even less, so that many rocks, whose nature was unknown 

 in the days of Prof. Phillips, are now recognized as having had a 

 volcanic origin. The pre-Cambrian volcano of St. David's has the 

 place of honour at the head of the list, and the great volcanic masses 

 of Lower Silurian age (Cambrian according to Prof. Seeley's classi- 

 fication) in North Wales and the Lake District are duly recorded, 

 whilst Scotland and Cornwall appear to have been the principal 

 seats of volcanic forces in Devonian times. Scotland was again 

 uneasy during portions of the Carboniferous epoch. The Secondary 

 period was not one of marked vulcanicity in these islands, though 

 there are many interesting volcanic rocks near Exeter and in other 

 parts of Devonshire associated with the Triassic strata of that 

 county. The Tertiary volcanic rocks of the north of Ireland and 

 west of Scotland and their results are dealt with in the concluding 

 portions of the chapter. 



After stating some of the results of volcanic energy from a dyna- 

 mical point of view, Prof. Seeley for the third time plunges into the 

 rocks. Accordingly we have a chapter on metamorphism, and one 

 on the distribution of gneiss and mica-schist ; and he concludes the 

 section of physical geology with the history of mineral veins, and an 

 account of the chief mineral deposits in Britain. Under the head 

 of British copper-mines we note that the " Carboniferous Lime- 

 stone " of Parys Mountain in Anglesey has long been productive of 

 copper. The age of the strata in Parys Mountain may still be a 

 matter of dispute ; but this is the first time we ever heard of those 



