50 
Looking at the position of the rivers it will now be seen that they run 
at right angles to the strike of these beds, which are inclined against 
the MiUstone Grit ridge, and that they cut through the upturned edges 
of the different strata. The theories that have been started to account 
for this apparent anomaly of the water taking the most difficult route 
to the sea are various. The probable reason is, at any rate for this 
district, that the faults have presented weak lines to the action of 
denudation. The lines marked on the large map have be^ kindly 
indicated to me by the gentlemen of the Geological Survey as repre- 
senting some of the faults which will be seen to run N.W. and S.E. 
The way in which denudation has not been affected by faults is, how- 
ever, a noticeable feature in some of the minor valleys. Eeferring to 
the large map of the valley of the Aire, kindly lent by your Secretary, 
it will be seen that the features of the locality are principally, if not 
altogether, due to the action* of denudation, the Eough Kock immediately 
underlying the coal being found at the top of all the hills in the 
neighbourhood. 
Contrary to the views of many good geologists I am disposed to 
think that in this district at least, in order to account for the great 
denudation, there has been a time when there was a much larger rain- 
fall than at present. Two points may be taken as some indication that 
this was the case; first, an examination of a section of a valley that 
has been cut through near Ponden, the rough sketch of which has 
been kindly given me by Mr. Dalton and Mr. Ellis. The sandstone 
rock has been cut thi'ough and the shale much worn down : at present 
drift covers the shale to some sixty feet, and there is little or no 
alteration in the cultivation or drainage higher up the streams. Another 
point of interest is that there are traces all over the highest parts of 
the moors, at depths of six or eight feet down in the peat, of tree 
roots, where no trees have been known to have existed in recent 
times. Lower down also we have traces of hazel cojjses, &c., where 
none have been known within the memory of man. It seems pro- 
bable that the whole of this high land, comprising many thousands of 
acres, was at one time forest, and so it is possible that the rainfall 
may have been formerly much greater. 
There ai-e traces of glacial action on the rocks of the hill sides, 
which show that other agencies were at work also in assisting in the 
process of valley making. Without disparagement to the powers of the 
Geological Survey, I may say the mapping of this district has not 
been a very easy task. The vast sheets of glacial and other drift 
lying high among the hills have given them much trouble, concealing 
faults of great dimensions, while the abrupt upheaval of the Limestone 
At Skipton throwing off the whole Yordale series or their representa- 
