58 NATURAL SCIENCE [j UL y 



in the neighbourhood of Budapest, and the spheroidal weathering of 

 dolerite at North Queensferry, given on p. 455. 



The second volume opens with the Great Whin Sill, which is pro- 

 visionally referred to the Carboniferous period. A considerable series 

 of volcanoes is then included as Permian, or possibly Triassic, on the 

 ground that " there is usually ample proof that the strata in question 

 [associated with them] are much later than the Coal-measures, while 

 their geological position and lithological characters link them with 

 the undoubted Permian series of the north-east of England." The 

 best known mass placed in this group is the upper portion of Arthur's 

 Seat, Edinburgh, which, the author maintains, is independent of the 

 older and true Carboniferous series. He thus supports Maclaren's 

 view of 1839, in opposition to its subsequent revision by its author, 

 and to the well-known paper by Prof. Judd. 



Some exceedingly pretty mapping of the fragmental materials in 

 a vent at Elie Harbour, Fife, is seen in Fig. 217 ; and the volcanic 

 sections of this district are again finely illustrated by full-page photo- 

 graphs. The capping of Titterstone Clee, in Shropshire, is referred 

 also to the Permian period. 



Then comes the great gap in our volcanic history, book viii. open- 

 ing with Cainozoic times. The plateau - basalts are attributed to 

 fissure-eruptions rather than to repeated flows from central vents ; 

 and a very valuable chapter (pp. 260-269) supplies an account of such 

 eruptions in recent times in Iceland. It is, however, pointed out that 

 the tabular sheets are composed of the union of successive flows, one 

 overlapping on the edges of another (p. 193) ; and the fact that cones 

 are formed along the lines of fissure, each sending out its separate 

 flows, is clearly brought out on pp. 264 and 265. The absence of 

 clear evidence of the connexion between our dykes and the superficial 

 flows is very candidly stated (p. 268). The recognisable vents, such 

 as Slemish in Antrim, and other well-known necks in the same 

 county, indicate more normal conditions of eruption. 



While there is this difficulty in correlating the intrusive basalts 

 with the lavas penetrated by them, we must also face the similar 

 difficulty arising from the lack of continuity between the gabbro 

 masses of Mull and Skye and the surrounding plateau-basalts. If the 

 dykes form the orifices for the extrusion of the latter, why may not 

 the heart of Skye have served equally as a great volcanic centre? In 

 both cases, the intrusive rock presented to us is that which last consoli- 

 dated in the vent ; its earlier and basal volcanic products may, how- 

 ever, remain to us in the surrounding lavas. Surely the great core of 

 Vesuvius is at this moment intrusive in the earlier lavas of its flanks. 

 The author recognises some such argument on p. 348, but will not 

 allow the site of the Cuillin Hills to have any direct relation to the 

 existing surface-products (p. 362). Granting that a number of small 

 vents suits the conditions recognised in Antrim, why may we not have 

 traces of more centralised activity in Mull and Skye ? The difference 

 of opinion between the author and Trof. Judd on this point appears 

 less fundamental, less to be insisted on, the more clearly we have laid 

 before us the relations of the dykes and plateau-basalts from the 

 fissure-eruption point of view. 



It can hardly be expected that Ireland should receive more detailed 



