MAPS AS GEOGRAPHICAL ILLUSTRATIONS 495 
Pennine escarpment of Durham and Yorkshire marks the edge of 
an eastward monocline of Carboniferous strata, faulted on the 
western slope, deeply scored by short valleys opening west- 
ward and by longer valleys descending eastward. The divide 
between these two systems of drainage offers an interesting line 
for study. 
The rugged hills of Yorkshire gradually degrease in height 
and merge into a lowland of Triassic strata, the northern 
extremity of the long irregular ‘‘inner lowland” by which the 
’ 
‘“oldlands” of Yorkshire, Wales and Cornwall are separated 
from the double scarped ancient coastal plain of the eastern and 
southeastern counties. Portions of the infacing scarps of the 
Yorkshire moors (Odlite) and the Yorkshire wolds (Chalk) are 
included in the southeastern sheets of this group, exhibiting the 
systematic arrangement of consequent, subsequent, and obse- 
quent drainage lines that characterizes the whole extent of the 
ancient coastal plain, from its beginning in Yorkshire southward 
to the English channel, as discussed in my paper on the Develop- 
ment of Certain English Rivers (London, Geographical Journal, 
V, 1895, 127-146). At their northern termination, the longitudi- 
nal features of the ancient coastal plain abnormally turn east- 
ward and are cut across in succession by the shore line, instead 
of continuing parallel to it, as in the normal arrangement of such 
forms: Flamborough head and the cliffs of Whitby present 
sections of the Chalk wolds and the Odlite moors. 
Ramsay's Physical Geology and Geography of Great Britain 
(6th ed.) and Woodward’s Geology of England and Wales (2d 
ed.) are the most accessible sources of information for this dis- 
trict and for England generally, but they give little physiographic 
detail compared to Geikie’s admirable book on Scotland. 
The central and southern part of England has not yet been 
covered by the new Ordnance Survey, and the hill shading of 
the older Survey is so inexpressive and often so uneven that no 
other groups for England are at present recommended. When 
issued, the sheets for the Weald (new series, 269-274, 285-290, 
301-306, 317-321, 332-334) will be very instructive. 
