January 7, 1898.] 



SCIENCE. 



35 



observation he has added an extensive and 

 critical acquaintance with the varied literature 

 of the subject. 



The book opens with a general discussion of 

 the characteristics of volcanoes, in which the 

 various types of eruption are illustrated by the 

 classical examples of Stromboli, Vesuvius, Kra- 

 katoa, the Hawaiian volcanoes and the colos- 

 sal lava sheets of the Deccan and the Columbia 

 valley. A description of the gaseous, liquid 

 and solid ejecta of volcanoes is followed by a 

 discussion of the form and structure of volcanic 

 cones and necks. Next are described the 

 characteristic types of subterranean intrusions 

 — dikes, sheets, plugs, laccolites and sub- 

 tuberant mountains. The opening chapter 

 closes with a brief discussion of the character- 

 istics of igneous rocks. A brief and popular 

 petrological section is by no means an easy thing 

 to write. The requirement of perfect accuracy 

 in brief and non-technical language is somewhat 

 like the pious old woman's order on her book- 

 seller for a very small Bible with very coarse 

 print. The following statements are inaccurate 

 and confusing: "If fused slag is cooled 

 quickly, crystals are not developed, but the 

 mass has a glassy or stony structure " (p. 68) ; 

 " if solidification takes place at this stage [after 

 formation of minute crystals floating in the 

 still fused material] , the ground mass becomes 

 a glass or felsite " (p. 112); " if the cooling is 

 rapid, a crystalline glass is produced" (p. 114). 

 The application of the name basalt to the 

 coarsely crystalline rock of the Palisades in- 

 volves an extension of the meaning of the word 

 unwarrantable even in a brief and popular 

 discussion. The statement that trachyte is 

 normally dark colored is certainly misleading. 

 "With Dana and others, Professor Russell holds 

 that some granites are truly metamorphic rocks. 

 The tendency at the present time is to derive 

 gneisses from granites rather than granites from 

 gneisses ; but we believe there is truth in both 

 views. 



The main part of the book, as implied in the 

 title, is occupied by the description of the ac- 

 tive and recently extinct volcanoes of North 

 America ; and the reader cannot fail to be in- 

 terested in the great variety of volcanic phe- 

 nomena so clearly described in its attractive 



pages. The eruption of Coseguina in 1835 al- 

 most rivals in tremendous explosiveness that of 

 Krakatoa in 1883. In Mount Taylor and its 

 companions are seen beautiful examples of vol- 

 canic necks. The volcanoes of the Mono val- 

 ley include a remarkable variety of volcanic 

 phenomena ; and the pages devoted to their 

 description, bright with the vividness of per- 

 sonal observation, are among the most fascina- 

 ting in the book. In Crater Lake we have a 

 magnificent example of a caldera formed by the 

 ingulfing of a volcanic cone. The reader will 

 readily sympathize with the author's enthusi- 

 asm over the majestic beauty of the snowy 

 cones that dominate the Cascade Range. In 

 the Columbia lava sheet we have the result of 

 colossal fissure eruptions rivaled only by those 

 of the Deccan. The Spanish Peaks are beauti- 

 ful examples of volcanoes dissected by erosion. 

 In Shishaldin we see a volcanic cone, the 

 symmetry of whose graceful, slightly concave 

 lines rivals the beauty of Fusiyama. In Bogos- 

 loff we have apparently a shapeless mass formed 

 by the sudden chilling of highly viscid lava 

 erupted beneath the sea. 



From the description of the volcanic phe- 

 nomena shown in North America the author 

 returns to the discussion of volcanoes in general. 

 The reader who has become familiar with such 

 widely varied details is in position to appreciate 

 the inductions which may be drawn from them 

 in regard to the mechanism of volcanic erup- 

 tion. Professor Russell adopts the view that 

 the interior of the earth is solid, but potentially 

 liquid at no great depth below the surface — a 

 view which seems to harmonize the teachings of 

 geology with those of physics. In common 

 with Reyer, the author attributes the relief of 

 pressure, which is the condition of local lique- 

 faction, and consequently of eruption, to the 

 formation of Assures. We are inclined to be- 

 lieve that the principal cause of such relief of 

 pressure and consequent liquefaction is found 

 in crustal elevation, as suggested by Archibald 

 Geikie.* Professor Russell rightly connects 

 igneous intrusions with volcanic eruptions, as 

 different phases of the same process. A true 

 and comprehensive theory of vulcanism must 

 include all phases of eruption and intrusion^ 



* Text-book of Geology, 3d edition, p. 268. 



