Geology of High Teesdale. 143 
strata; and where the denudations are considerable, sometimes 
reach the lower part of the series of beds, which forms the 
foundation of the mountains. But on ascending towards the last 
ramifications of the rivers, the inclination of the vallies always 
begins to exceed that of the strata, so that we again cross some 
of the beds, which, by their natural rise, had ascended from the 
region we had left behind. For example:—In following the 
course of the Tees towards its source, we first traverse the plain 
of the new red sandstone, and then cross the line of the mag- 
nesian limestone, and enter on the carboniferous series. Con- 
tinuing to ascend, we pass over the lower beds of the coal 
formation, and at length reach the beds associated with the 
metalliferous limestone. The successive members of the new 
series occupy the banks of the river for several miles. But on 
reaching the upper part of High Teesdale, we may ascend, by 
one of the ramifications of the river, towards the top of the 
chain, and find a part of the same series of strata which we 
had before passed over, presented to us in an inverted order. 
The structure we have described, is evidently favourable to 
a minute examination of the geological relations of each district, 
and the existence of a great many rich metalliferous veins in 
the same region, has directed the attention of practical men to 
the phenomena of stratification. Hence, many excellent sections, 
both of the calcareous, and carboniferous series, which form the 
eastern flank of the mountain chain, have been already given to 
the public*. Sections of this kind, made in situations which 
are considerably remote from each other, give us every infor- 
mation respecting the analogies of structure and composition ; 
but, as was before observed, seldom enable us to identify the 
subordinate members of the prevailing formations. 
* See Forster's Section of the Lead-measures. Winch’s Paper on the Geology of 
Northumberland and Durham, Geological Transactions, vol. IV. &c. 
