148 
HUGHES : INGLEBOROUGH. 
felspathic rock with small flakes of black mica, which forms one 
of the three principal dykes seen here. 
We must not imagine that the faults in a district like this 
took place suddenly. These faults are merely easements during 
the folding of the rocks, and therefore, as the folding was a slow 
process, commensurate with the great denudations that planed off 
the land as it was raised, and with the sedimentation which was 
the necessary accompaniment of that denudation, so the faults 
must have been going on continuously or spasmodically while 
deposits were being laid down. They, however, may indicate 
periods of more rapid movement, in which the rocks which had 
Fig. 7. 
not time to bend must break, and they also point to greater 
inequalities of surface and generally suggest periods of locally 
changing conditions. 
Perhaps there may be some reason for suspecting that the 
Dam House Bridge fault near Austwick was going on during 
the accumulation of the basement beds of the Silurian from the 
difference in the character and thickness of the conglomerate on 
the north or upthrow side of the fault as compared with that on 
the south side, and from the great paleontological change which 
marks the incoming of the Silurian and points to altered geo- 
graphical conditions. 
