Aprii. 13, 1883.] 



SCIENCE. 



281 



surface of the Laureiitiau gneiss of western 

 Scotland was anterior to the deposition of 

 the Cambrian sandstones, and that there are 

 minor domes and bosses of crj'stalline rock, 

 coutinnons with those of the exposed surfaces 

 supposed to bear the marks of modem glacial 

 action. The conclusion from this would seem 

 to be, that the latter agenc_y has done little 

 more than groove and polish these ancient 

 rounded surfaces, from which a later erosion 

 had removed the covering sandstone. Whether 

 the pre-Cambriau erosion was glacial is a 

 question which Geikie does no more than sug- 

 gest. In this connection, the existence of a 

 state of chemical deca^' as a necessary- prelimi- 

 narj' to the erosion of crj-stalline rocks should 

 not be lost sight of.^ We believe that such a 

 process predetermined the contours of their 

 present eroded surfaces. 



The question of the erosion of ancient land- 

 surfaces is further discussed by Geikie in a 

 lecture here republished, gi\'en b3- him before 

 the Eoyal geographical society in 1879, on 

 The geographical evolution of Europe. In 

 this, b}- aid of the data of geology, he gives a 

 chapter on what has elsewhere been called 

 paleogeography. Geikie shows that the frag- 

 ment of primeval Europe alreadj^ noticed, was 

 a part of a great pre-Cambrian area, to which 

 parts of Finland and Scandinavia belonged, 

 and from which was derived the sediments that 

 built up the Cambrian and Silurian series of 

 Great Britain and western Europe. These 

 lower paleozoic rocks in Great Britain alone, 

 he assumes to cover an extent of 60,000 a 

 miles, with an average thickness of 16,000 

 feet, or 3 miles, which figures he considers 

 below the mark, — making not less than 180,- 

 000 cubic miles, equal to a mountain range 

 from the North Cape to Marseilles, or 1,800 

 miles long, 3 miles high, and 33 miles wide. 

 This, he well remarks, represents but a frac- 

 tion of the material thus derived ; , since in the 

 seas of that time, extending far eastward, were 

 also laid down great thicknesses of paleozoic 

 rocks, continuous with those of the British 

 isles. Calculations of this kind, applied to 

 North America, give us still larger notions of 

 the erosion of great pre-Cambrian areas be- 

 longing to some Palae-Atlantis. 



It would be profitable, with Geikie's sketches 

 as our guide, to glance at the glaciers of Nor- 

 way, the ancient volcanoes of Auvergue and 

 of north-western Europe, and to accompany 

 him, in his excursion in 1880, into our western 

 states, where his quick ej-e readily compre- 

 hended many of those I'emarkable characteris- 



1 Harper's annual record of science, etc., 1873, p. xlix. 



tics which make the transcontinental j6urney 

 from the Atlantic to the Pacific a geographical 

 education. 



In his lecture on assuming his late post of 

 professor of geology at Edinburgh, in 1871, 

 Geikie has happily delineated the characters of 

 the Scottish school of geology, and traced 

 manj' of the characteristics of its masters — • 

 Hutton, Playfair, and Sir James Hall — to the 

 local peculiarities of their native land, with its 

 cr3'stalline, contorted, and unfossiliferous rocks, 

 so unlike the regions in which the early Italian 

 school laid the foundations of geologj'. It is 

 instructive, in this connection, to reflect how 

 the great and simple outlines of American 

 paleozoic stratigraphj', as displayed in the 

 Appalachian basin, led to the grand concep- 

 tions of structural geology formulated by the 

 brothers Rogers, by James Hall, and bj* Lesley, 

 and how the remarkable features of our west- 

 ern regions, have taught our geologists of the 

 younger generation lessons which have enabled 

 them so greath* to advance the science, and to 

 correct the views of their predecessors, both in 

 the old and the new world. 



We hope on another occasion to notice more 

 in detail some of the questions raised in this 

 instructive volume, in which every student of 

 geology will find something to instruct him, 

 and to stimulate thought. 



VERTEBRATE ANATOMY. 



A handbook of vertebrate dissection. Part ii. How 

 to dissect a bird. By Prof. H. Newell Mar- 

 tin and Dr. William A. Moale. New York, 

 Macmillan, 1883. 4 + [86] p., 3 pi. 12°. 



This second part of the handbook is quite 

 up to the standard of the first. It is compre- 

 hensive, without going bej-ond its intended 

 limits ; the descriptions are clear and well- 

 worded ; the subjects selected for illustration 

 are those most needing it, viz., the more, com- 

 plex parts of the skeleton ; and the diagram 

 constituting figure 5 will prove very useful in 

 clarifying certain ideas of the learner. 



The method of treatment is well calculated 

 to bring out the observational power of the 

 student ; and the fact that the avian, rather 

 than the generic and specific characters, are 

 made prominent, renders the book much more 

 widely useful, and also serves to commend it 

 to practical workers in zoology. With the 

 other books of this series, which are to treat 

 in a similar manner of a rat, a bony and car- 

 tilaginous fish, and one of the large, tailed am- 

 phibia, or Urodela, we shall be supplied witii 

 a book which has long been needed in America. 



