CLENT HILLS BRECCIA. 
35 
country consists of a number of basins bounded by mountainous 
country. The margins of these desert plains consist of a long slope 
of gravel and boulders extending in some cases five to ten miles 
from the base of the hills. The greater part of the slope consists of 
sand and pebbles, the latter more or less angular and mixed with 
large blocks all derived from the adjacent hills. Fragments 2ft. to 
3ft. in diameter are not uncommon even at a distance of a mile or 
two from the base of the hills, but only near places where small 
streams run. He states that, bearing in mind that all accumulations 
of detrital matter are due to arrest of motion, whether partial or 
total, in the transporting agent, we can easily understand that the 
rainfall on the Persian hills may suffice to wash down as far as 
the sides of the valleys those fragments which by the chemical 
agency or the action of frost are loosened from the hill sides ; but, 
when the momentum given by the steepness of the incline is at an 
end, the quantity of water drained from the’surface is insufficient to 
transport the debris to a lower level; all that it can do, is to leave 
the detritus in a long slope, the surface of which is arranged by the 
wash of rain. 
Have we not here the origin of the Clent Hills Breccia ? Such 
denosits on a small scale can be seen on the sides of most mountain 
j. 
ranges. The best example I know is at Wastwater, in the Lakes, 
where we get the screes so well known to all climbers. The 
eastern side of the lake is bounded by a ridge, which is rotten and 
fast crumbling away, and the detritus is forming a long scree slope 
extending right into the lake. Cases of violent succussion of rocks 
are Tryfan and the Grlyders, the tops and sides of which are littered 
with gigantic blocks. I therefore submit to you that the rocks 
have travelled but a short distance from their original site, and are 
derived from a boss, peak, or ridge, composed partially of Llandovery 
Sandstone, resting unconformctbly on the Cambrian ; that the re¬ 
aggregation of the rocks took place in the way described in Mr. W. 
T. Blandford’s paper, or by the violent succussion of the rocks by 
the displacement following the carboniferous period. It may be 
that we should assign both these as the cause of detachment from 
the parent rocks. Every fact so far points to the rocks being 
February, 1893. 
