554 



NATURE 



{Oct. 13, 1887 



that lies spread below him, can for a moment gainsay the 

 fact, whatever may be his opinion as to the conclusions 

 drawn from it : by nearly all geologists they are accepted 

 as the only reasonable explanation. But we need not 

 go to the Highlands to find instances of old table-lands, 

 which have been trenched by sub-aerial denudation ; and 

 perhaps some examples on a smaller scale may be more 

 easily appreciated by beginners. An admirable case is 

 found in the south-west of England. Anyone who walks 

 up from Bristol on to Clifton and Durdham Downs cannot 

 fail to be struck by the remarkable evenness of their 

 surface ; after a long pull up a succession of steep inclines 

 you find yourself all at once on a plateau as flat as an 

 alluvial meadow. By dropping down into the gorge of 

 the Avon, an equally good instance of a river-trench cut 

 through the plateau is supplied, and at the same time 

 proof is furnished that the present surface, so suggestive 

 of level-bedded strata underneath, really cuts sheer across 

 beds tilted at high angles, broken by faults, and bent into 

 complicated folds. The flat top runs on along the line of 

 limestone hills that connect Bristol with Clevedon ; it is 

 specially noticeable around Clevedon ; and after we have 

 crossed a broad depression occupied by softer Coal 

 Measures and Secondary rocks, we find it reappearing in 

 the flat-topped Mendips. Nor is it confined to the 

 exposed portions of the limestone area. Where that rock 

 is covered by Secondary strata, shafts sunk in making 

 tunnels and other excavations show that the newer beds 

 rest on an almost level surface of Palaeozoic rocks. Over 

 the whole country there can be traced, whether exposed 

 or hidden, the clearest remnants of an old pre-Triassic 

 table-land. 



We also find in the Avon gorge that the limestone has 

 undergone disturbances smaller in amount, but identical 

 in kind, with the gigantic displacements of Sutherland 

 and Ross-shire, of which a short account is given in the 

 present volume, and which are most graphically depicted 

 in a longitudinal section by Mr. Peach. Anyone who 

 wishes to understand what '' thrust-planes " are, will find 

 here very good miniature examples. An announcement 

 of the greatest interest is made by the author while 

 touching on this part of his subject. He states that the 

 general assemblage of the organisms in the Durness 

 Limestone recalls none of the Lower Silurian formation 

 of Wales, but rather some of the still older groups of the 

 Lower Palseozoic series of Canada. This reminds us that 

 Lapworth finds the best paleeontological parallel to his 

 Moffat series in North America. To speculate on the 

 geographical distribution of animals at so distant a time 

 is risky work, but we may be tempted to conjecture that 

 one great life province included both Scotland and North 

 America, while Wales and Central Europe formed parts 

 of another. Maybe the buried Archaean ridge, the tops 

 of which stick up through the Secondary rocks of the 

 centre of England, formed a portion of the barrier between 

 the two. 



But to return to the book before us. Having made 

 good his contention that there was a time when the whole 

 of what is now the Highlands was a broad undulating 

 table-land, and that all its manifold diversity of feature 

 has been carved out by sub-aerial denudation, the author 

 takes us to the hills, the valleys, and the lakes, and en- 

 forces his conclusion with a wealth of illustration and a 



series of word-pictures of the most vivid character, which 

 can be appreciated only by a study of the work itself. 

 The Southern Uplands he treats in a similar manner, and 

 incidentally he puts in a strong plea for a district which 

 possesses much beauty of an unobtrusive kind, but which 

 is apt to be condemned as bare and monotonous. 



The Midland Valley is next brought before our notice. 

 How delightful is even a railway ride on a bright sunny 

 day over this charming country ! It is in the main aland 

 of broad rolling hills and wide valleys, well wooded and 

 well watered, pleasant to the eye from its brightness and 

 its richness. But, if this were all, there would be, it must 

 be confessed; somewhat of a sameness about it that 

 might be accounted tiresome. But it is redeemed from 

 any risk of monotony by numerous ranges or groups ot 

 hills, of moderate elevation, but high enough to tower well 

 above the general level, of ruggeder and wilder forms 

 than the flowing contours of the body of the country, and 

 many of them peaky and mountainous in outline. These 

 are formed of the products of the old volcanoes which 

 were once sprinkled so thickly over the district : their 

 rocks, being harder than the sedimentary beds among 

 which they occur, have been able better to hold out 

 against denudation and have therefore not been worn 

 down to so low a level. A very similar little tract is found 

 in West Shropshire, where the Wrekin, Caer Caradoc, 

 the Cardington Hills, and some other hill-groups — none 

 very high, but all mountains in miniature — introduce a 

 delicious diversity in the rich pastoral country of the 

 Severn valley. 



So far we have looked at the book solely from a scienti- 

 fic point of view, and, if no more were said, a suspicion 

 might arise in the minds of the readers of this notice that 

 perhaps the work was a trifle dry. But a very slight ac- 

 quaintance with the book itself will dispel any misgiving 

 on this head. No one has done more than the author to 

 elucidate the geology of Scotland, but he knows and 

 loves his fatherland too well to look upon it merely as a 

 field for geological research. Legend and history, old 

 ballad and modern poetry, have all been pressed into his 

 service, and he interweaves into his narrative allusion 

 and quotation in a way that enlivens even the most tech- 

 nical parts of the volume. The chapter on " The Influ- 

 ence of the Physical Features of Scotland upon the 

 People" shows well what a vast amount of human interest 

 attaches even to so special a science as geology. 



If the intending tourist in Scotland will before he starts 

 read enough of this book to enable him to comprehend 

 its general drift and line of argument, and if he will then 

 take the book with him and study on the ground such of 1 

 its illustrations and examples as lie on his road, he willj 

 ever after thank the author for having supplied him with 

 a new pleasure. One great charm of travel in Scotland; 

 is that it is ever leading us through scenes rich in historic I 

 associations. The enjoyment derived from such a source' 

 may be vastly enhanced by the aid of this book ; for hej 

 who has mastered its contents will feel an interest not] 

 in the events of the human epoch only, but will see in i 

 every peak, hill-side, valley, and lake that he passes the \ 

 monuments of a history which carries him back through 

 that long vista of the ages which geology has opened out 

 to us. 



A. H. Grei 



