THE ORIGIN OF OUR ENGLISH SCENERY. 
61 
The history of the origin of our rivers and their valleys is a 
large subject, and one which opens up many difficult questions 
in physical geology. The subject was first clearly brought into 
notice by the late Mr. Jukes ; and Professor Ramsay, who has 
paid great attention to it, has treated of the origin of several of 
our most important rivers. As it is largely connected with the 
origin of much of our English scenery, we must give some at- 
tention to the results of their observations, but before doing so 
it may be well to point out in a general way the origin of the 
great features. 
Many years ago Professor Ramsay noticed that in drawing a 
section through Wales, through the more hilly or mountainous 
regions, a line might be drawn from one end to the other, 
which would touch, or nearly touch, all the more important 
elevations. The whole of the rocks of palaeozoic age which 
form these regions are much disturbed or contorted, being bent 
into folds, and at the same time irrespective of the shape of the 
hills. He demonstrated that, while filling up the valleys in 
imagination, there yet remained a vast amount of material that 
had been removed above the line which touched the tops of the 
hills. This line indicated to him a plain of marine denudation. 
Before the tract was elevated to its present position the sea 
worked away gradually, as it does now on many parts of our 
coasts, such as at Watchet or near the mouth of the Thames at 
Southend, forming a plain of rock (whether stone or clay) 
barely covered at low tide. The plain formed in Wales was, of 
course, a very extensive one, and then after the area was ele- 
vated atmospheric denudation came into play. Rents, joints, 
and fissures in the rocks no doubt gave a first direction to many 
of the valleys, which have been enlarged by rain and streams 
and rivers, and even by glaciers. So that really the main fea- 
tures of Wales, as we now see them, are due chiefly to fresh- 
water denudation, although there is every reason to suppose 
that the sea exercised some modifying influence on the land 
during the long course of ages and the many changes it has seen 
since the later paloeozoic times. 
We may now turn to the escarpments of the oolites and 
chalk, which are the next grand features we have to consider. 
Professor Ramsay believes that the lias and oolites entirely sur- 
rounded the old land of Wales, passing westward through what 
is now the Bristol Channel on the south, and the broad tract 
of new red formations that lie between Wales and the Lanca- 
shire hills, now partly occupied by the estuaries of the Dee and 
Mersey. He considers, too, that the chalk in its day also 
spread far to the west, covering unconformably the half-denuded 
oolites, till in its early beginning it also abutted upon the 
ancient land formed of the palseozoic strata of Wales, and by- 
