VOL. XVI. (3) THE LOWER SEVERN 247 
Severn. Here, in my view, is a relic of a former looping 
of the Severn and the Wye, of which other examples may 
be seen, above and below this one. 
Fic. 3.—Relic of an old looping of streams, when flowing at a higher level, round 
Ebrington Hill. The shading shows the outline of the hard Marlstone 
which is partly covered by Upper Lias and Inferior Oolite. 
If, in a drainage area, there happen to be an up-lifting 
of rock-formation, continuous along an extended line, the 
portion of the area along this out-crop will be more 
broken and more easily denuded than any other line, and 
so the river-channel may form here, and if this line gives 
access to the Sea, it may become a permanent, principal 
channel. Now the combined Severn-Avon does run 
along such a line, and is, by this line of out-crop cut off 
from having any part in the river-system of the Thames 
beyond the Cotteswold Hills. This has always seemed 
to me to be a simple and satisfactory explanation of the 
line of the Lower Severn, but it has not, so far as I know, 
been formally accepted by anyone. Still, I say, the 
occurrence of a river-valley along an anticlinal axis is very 
common, and is clearly due to the over-stretching of the 
strata along the summit of the double incline, which, being 
broken, are easily denuded. The Severn does, as a fact, flow 
along an anticlinal axis complete in the lower part of our 
