99 
that the old plains of marine denudation began to be re-exposed, 
the rivers still went on, as nearly as possible, in their old direction, 
regardless of the differences in hardness and in power of resistance 
to atmospheric forces presented by the rocks they were traversing. 
Now, all the rivers flowing outwards from the Lake District have 
had to cut their way across rocks that vary greatly in their rates of 
destructibility. One rock that will stand exposure to the weather 
for hundreds of thousands of years, and be in the end not much 
the worse for wear, may overlie, or may pass beneath, another rock 
that wastes away to an appreciable extent in a single lifetime. 
Only to-day I have been looking at two sets of glacial strie that 
I first examined no more than ten years ago. The first set is that 
on the surface of the sandstone we looked at at Blencowe to-day, 
which strize are just as sharp as they were ten years ago. The other 
set is close to Penrith, and occurs on limestone, near Redhills. 
Ten years ago they were quite fresh, and clear enough to catch the eye 
of a casual passer by ; but exposure for only ten years has resulted in 
reducing what was then a smoothed, or even polished surface, to 
_ one that is now perceptibly rough to the feel. The effect of the car- 
bonic acid in rain water has been to dissolve and carry away part 
of the limestone, and to remove some of the traces of glacial action 
with it. 
These two cases well exemplify what takes place on a larger 
scale all over the district. The beds around us here in Greystoke 
Park, first appeared as a nearly uniform slope, which was formed 
by the edges of rocks that present very different powers of resistance 
to the action of the weather. These inequalities of resistance to 
waste and decay may be slight in themselves, yet when the rocks 
are acted upon for a very long period, these differences tell up, 
and in the end give rise to diversities of surface of so much 
importance that one is disposed at first sight to attribute them to 
causes acting with more intensity. 
VARIED HISTORY OF THE PETTERIL. 
Our rivers here began to flow when the surface then existing at 
this point was nearly or quite two thousand feet higher relatively 
