1897] SOME NEW BOOKS 57 



Page after page attests the energetic field-work on which each series 

 of results is based, though now and then acquaintance with the 

 ground is required, before w T e can detect how much is due to a grasp 

 of the features of the scene itself, and how much is culled from the 

 drier field of published memoirs. 



We must not attempt, chapter by chapter, to touch on the 

 numerous new suggestions, or the revisions of previous work, con- 

 tained in the description of each special area. On p. 145, we note 

 that the Cambrian is stated to pass down conformably into the 

 Pebidian of St David's, which is included with it, the Arvonian and 

 Dimetian being intrusive ; and no pre-Cambrian rocks are tolerated 

 here. But in other places the earlier work of the survey is candidly 

 set aside, where the personal investigation of the author has led to a 

 change of view. Here and there, work remaining to be done is 

 indicated, as in the Malvern range (p. 170), and in the important 

 Borrowdale series (p. 227). 



In the latter case, the discussion given in the present work does 

 much to fill the gap, and is a fine example of the caution with which 

 such altered masses must now-a-days be approached. We have done 

 with the broad structural diagrams, accompanied by ' theories of the 

 earth,' which had to serve as a basis for future observations, at a 

 time when the labourers were few ; and Sir Archibald Geikie writes 

 of the map of the lake district, " so rapid has the progress of certain 

 branches of geology been since these sheets were published, that the 

 map is even now susceptible of considerable improvement." 



A strikingly new chapter, embodying results hitherto unpublished, 

 or, perhaps, only hinted at in the annual reports of the Geological 

 Survey, deals with "the Silurian Volcanoes of Ireland" (pp. 239-256). 

 "We note than an Arenig age is suggested for the crushed tuffs of 

 eastern Tyrone, formerly regarded as ' Dalradian ' ; but " no recognis- 

 able radiolaria have yet been detected " in the associated cherts. 



An interesting point in the description of the Old Eed Sandstone 

 eruptions is the occurrence of infillings of sandstone in the cavernous 

 hollows of lavas poured out under water (pp. 283 and 333). In some 

 cases, these sandstones are even stratified, reminding one of the 

 material deposited in the interstices of a coral-reef. 



"We are glad to note, on p. 346, the decided attitude taken up 

 with regard to the correlation of the Dingle Beds. Irish geologists 

 have, more or less, played with this important stratified series, usually 

 referring it to the Silurian, although it clearly caps the Ludlow beds. 

 Since Jukes led an attack upon the Devonian system as a whole, an 

 attempt has been made to do without that system in Ireland, the 

 Upper Old Red Sandstone being carried bodily up into the Carbonifer- 

 ous, and the lower thrust down into the Silurian. No man living can 

 speak with better authority on this point than Sir Archibald Geikie. 



The first volume closes with a superb series of full-page photo- 

 graphs of the Carboniferous volcanic phenomena of Scotland. "While 

 these recall the w T ork done by the Geological Survey of the United 

 States, we can only regret that in our own islands their publication, 

 on this ample scale, has been reserved" for private enterprise. "We 

 cannot resist mentioning by name the view of the agglomerate of the 

 Binn of Burntisland (p. 431), which equals the fine Cainozoic sections 



