224 
any rate, I think Professor Phillips was quite justified in 
declaring, many years ago, that a survey of the whole line 
of the Ure and other contiguous valleys " appears to refute 
the opinion that the existing drainage waters have carried 
off much of the detritus." 
On the flatter parts of Eombold's Moor, rain-water, by 
being retained, has favoured the growth of peat, but on the 
sides of the moor, where facilities are afforded for the water 
running off, rain-torrents have excavated a number of 
narrow, deep gullies, which give a very attractive variety 
to the scenery. But it is worthy of notice that when rain- 
water is not confined in a well-defined channel, it does but 
little in channeling the surface or destroying the rocky 
ramparts of the moor. The fresh- water gullies have in a 
great measure been formed in previously-existing and pre- 
viously-spread-out detritus and drift, some of these gullies 
being from 30 to 40 feet deep. 
There are few parts of the Millstone Grit districts of 
Yorkshire where the appearance of devastation, in the shape 
of scattered and heaped-up blocks, is so strikingly presented 
as on the north side of Rombold's Moor, near Ilkley. At 
first sight it is natural to conclude that a convulsion has 
broken up the crust of the earth, and dispersed these blocks ; 
but a little investigation will be sufficient to dispel this idea ; 
for though it be true that the strata have been shattered in 
many places, yet no shattering agency could have thrown or 
carried the blocks to the positions they now occupy; but I 
think these positions may be explained by four modes of 
geological transportation. 
First. The mere tumbling down of blocks through gravi- 
tation, during or after the period of the formation of the 
cliffs and rocky slopes. 
Secondly. The fall of blocks which have been loosened by 
rain. 
