J. Clifton Ward — On Rock-fissuring. 247 



- Against (3) an objection might be raised that they occurred only 

 among certain rocks of the district, whereas faults would be likely 

 to be found without any such marked restriction. But I do not 

 think such an objection would hold ; the non-occurrence of the 

 fissures of this class among the Skiddaw Slate mountains is probably 

 due to the nature of the rock ; if fissured gradually, or even sud- 

 denly, the readily splintering and shivering slate would close the 

 crack almost directly, so that it would be unperceived, whereas 

 among the hard and hlocky rocks of the Volcanic Series the fissure 

 would stand open, or have large angular blocks wedged in it. 



There is certainly no reason why faults should not now be in pro- 

 cess of formation beneath our feet ; the action may be imperceptible 

 because so slow, and denudation may be obliterating any outward 

 marks of faulting as fast as they tend to be formed. Many faults 

 may be produced among rocks deep down, without the topmost 

 layers being disturbed, as is occasionally proved in collieries, where 

 a fault sometimes affects a lower bed of coal but not an upper ; but 

 in some cases, at all events, the faulting action might reach the 

 surface. If such action took place gradually, one would not expect 

 to meet with much surface evidence of it among soft rocks, in 

 which abrupt inequalities would be smoothed down as fast as 

 formed ; or over those areas which have only been dry land for a 

 short period ; but rather among hard jointed rocks, and over areas 

 which have existed as dry land for long periods of time. Now as 

 regards this last point, I think there is every evidence to show that 

 the mountain district of Cumberland and Westmoreland has existed 

 as an area of dry land ever since the close of the Carboniferous 

 Period, or perhaps since that of the Old Eed, with the exception of 

 the partial submergence during Glacial times, when the higher 

 mountain tops were even then above water. Still the time since 

 the close of the Glacial Period is itself so great, that longer periods 

 may be left out of reckoning, and moreover, any open fissures or 

 great rents would probably be completely effaced by the movements 

 of snow and ice over a rocky country strewn with fragments. 



On the whole, I am rather inclined to think that supposition (2) 

 is the simplest, and the simplest is generally the truest ; but at the 

 same time the mind is greatly tempted to dwell on any indications 

 of great forces — the former effects of which we see around us — still 

 working quietly and effectively. 



Before closing the subject, I should like to say a few words upon 

 the singularly stony nature of the summit of Scafell Pikes and some 

 other mountains. In the case of Scafell, the summit of the moun- 

 tain as far as Great End is thickly strewn over with lai'ge rough 

 blocks of stone, so that one's progression is often limited to jump- 

 ing from block to block. The masses are not travelled, but are 

 evidently lying only just out of place. Last summer I carefully 

 examined some of the rock-masses which were still in place, and 

 found them often much jointed and fissured, the blocky fragments 

 tending to topple over into the fissures. At one spot this was par- 

 ticvdarly well seen, — a fissure traversed a well-jointed mass of close 



