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 
