130 Bibliographical Notice. 



After a day's hunting a geological map has explained why white 

 mud and brown, black clay and white chalk, peat-bog and sand-hills 

 have succeeded each other so quickly in the run across country, — or 

 why one long gallop carried along with it the uniform splashing of 

 yellow mud with little change. Of course, now-a-days, geological 

 maps are hanging up in halls and studies far more frequently than 

 in times past ; and instead of trying to find causes for differences of 

 peoples and lands in county-boundaries and political divisions, we 

 look to mountains and valleys, hills and dales, with their varying 

 geological structures, as land-marks among men, whether in counties, 

 provinces, or continents. The traveller in unknown lands brings 

 home but a meagre account of the geography of the country he would 

 describe if he knows not its real structure : he may make a model 

 even of its heights and rivers ; but, without a knowledge of its strata, 

 his model will fall as short in actual worth as a badly painted por- 

 trait. Not only will a full appreciation of structural peculiarities of 

 hill and cliff be wanting, but none of the links of analogy or identity 

 that bind it on to the strata of other lands can be indicated ; and, 

 like the nameless ruined column, it waits for further elucidation. 



At home our geological maps are progressing rapidly towards per- 

 fection. Amateur workers have accumulated observations for more 

 than fifty years ; and within about twenty years a systematic plan of 

 geologizing the British Isles has been carried on by the State. The 

 Government Geologists, well trained, enthusiastic, and yet cautious, 

 fairly using the results of fore-gotten knowledge, have worked as 

 quickly as their limited numbers would permit. Thus they have 

 gone over "Wales, the South of England, much of the Midland 

 Counties, some parts further north in Scotland, and a large part of 

 Ireland. From these results Prof. Ramsay has carefully produced 

 the Map of England and Wales before us, filling up unsurveyed areas 

 with the results of amateur and casual work. In this third edition 

 we may easily see where earlier mapping has given way to the work 

 of adepts and professional geologists, working over every inch of the 

 ground, going along the whole line of an outcrop, trusting nothing 

 to fancy or the memory, but examining and noting with precision, 

 day by day. In this way the broad areas of colour, with boldly 

 rounded and entire boundary-lines, filled in as the result of a holi- 

 day's research or rapid sketch-work, must be replaced by the labo- 

 rious entanglement of outlier, inlier, and jagged border of outcrops 

 along broken ground, carrying at once an appearance of truth to the 

 experienced eye. Thus in the so-called •' London Basin" more de- 

 tail in the northern border of the Tertiary beds is now given ; and 

 the Bagshot formation and the alluvium of the Thames are far more 

 correctly delineated. The Tertiary outliers at the west of this area, 

 and those between it and the " Hants basin," are altogether rear- 

 ranged, patches of "Drift" apparently having formerly been mis- 

 taken in many instances. The Wealden area is now far better cha- 

 racterized in accordance with the late researches of the Geological 

 Surveyors, who have worked out its complicated structure as care- 

 fully as if it were a coal-field ; nor indeed do we know but what it 



