Revieivs — W. J. Harrison's Texthooh of Geology. 329 



"The relics of former volcanoes in this country furnish ample 

 proofs to dispel these common misconceptions. They show that not 

 a single crater anywhere remains save where it has been buried 

 under lava ; that no trace of the original cones has survived, except 

 in a few doubtful cases where they may have been preserved under 

 subsequent accumulations of material ; that in the rugged tracts, 

 where volcanic action has been thought to have been most rife, there 

 may be not a vestige of it, while, on the other hand, where the 

 uneducated eye would never suspect the presence of any remnant of 

 volcanic energy, lavas and ashes may abound. We are thus pre- 

 sented with some of the most impressive contrasts in geological 

 history ; while, at the same time, this momentous lesson is borne in 

 upon the mind, that the existing inequalities in the configuration of 

 a landscape are generally due far less to the influence of sub- 

 terranean force than to the action of the superficial agents which are 

 ceaselessly carving the face of the land. Those rocks which from 

 their hartlness or structure are best able to withstand that destruc- 

 tion rise into prominence, while the softer material around them is 

 worn away. Volcanic rocks are no exception to this rule, as the 

 geological structure of Britain amply proves." 



The first volume treats of the nature and causes of volcanic action, 

 and deals with modern volcanoes. The author next considers 

 ancient volcanoes, and the proofs of their existence to be derived 

 from the nature of the rocks erupted from the interior of the earth. 

 The various types of old volcanoes are described as the Vesuvian 

 type, the plateau or fissure type, the Puy type, and the relative ages 

 to be assigned to these ancient volcanoes. This leads on to the 

 consideration of underground phases of volcanic action, as the in- 

 trusive series, vents of eruption, necks, inward dip of rocks towards 

 necks, subterranean movements of the magma, dykes and veins, sills 

 and laccolites, bosses, etc. The influence of volcanic rocks on the 

 scenery of the land. This is followed by chapters on Cambrian and 

 Pre-Cambrian volcanoes, and on the volcanoes of Silurian, Devonian, 

 and Old Ked Sandstone time. 



We hope next month to take up Volume II, and give a further 

 idea of the nature and extent of this, the latest of Sir A. Geikie's 

 geological and literary ventures ; by no means the first, and we trast 

 it may not be the last, which he may contribute to the geology of the 

 Victorian era, a period which covers the best years in the lifetime of 

 our science. 



II. — A Textbook of Geology: Intended as an Introduction 

 TO the Study of the Rooks and their Contents. By 

 W. Jerome Harrison, F.G.S. 8vo ; pp. vii, 343. (London : 

 Blackie & Son, 1897.) 



EIGHT years ago Mr. Harrison's " Elementary Textbook of 

 Geology " appeared as one of Blackie's Science Textbooks. 

 It has now developed into the above-mentioned work, which, as the 

 author states, is nominally the fourth edition of his little book. 

 A somewhat larger page and a larger type have now been adopted, 



