135 



ago in the neighbourhood of Pensford, and there is every 

 probability that an outlying basin of the series may exist 

 there, but as there is a decided tendency to deterioration in 

 proceeding northwards, it is a question whether at so great a 

 distance it may be of much practical value. We now pass 

 on to the 



GREAT FAULT (OR 100 FATHOM FAULT). 



This is the largest fault of the district, and it has been 

 proved from Timsbury to Bramhill Farm, not far from the 

 village of Kilmersdon, south of which it has not been 

 traced. It is a downthrow west, varying from 120 feet at 

 Timsbury to 384 feet at Kilmersdon, and reaching its fullest 

 development at Clandown, where it has been proved to be 

 720 feet. 



Of many faults it is difficult to say whether they are 

 " downthrows" or " upthrows," whether the strata on one side 

 have dropped into some chasm far down in the earth's crust, 

 or whether they have been upheaved by some force from 

 beneath on the other ; but as to the Great Fault there is little 

 room for doubt. Taking the average inclination of the strata 

 and their levels on its eastern side in connection with the 

 levels of the strata and their inclination at a point half a mile 

 to the west of it, we are led to infer that they originally formed 

 one uniform gradient. The beds have evidently dropped 

 down on the west side of the fault, the veins rising at a high 

 angle for the first hundred yards as they recede from it, 

 and then resuming the usual inclination. 



The fault is interesting, inasmuch as on the deep side of it 

 at Clandown we find the greatest development of the coal 

 measures to be met with in the district, a greater thickness 

 of strata above the upper series having been preserved fi-om 

 denudation than is to be met with at any other j^art of the 

 coaJ field. The only cause for regret is that in the additional 



