Editing Dinantian and Namurian rocks of Bolton Abbey and Trollers Gill - an excursion

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==== Locality 3 [SE 075 543] ====
 
==== Locality 3 [SE 075 543] ====
  
Walk 100 m upstream to a point across the river from a small anticline ([[:File:YGS_YORKROCK_FIG_06_02.jpg|Figure 6.2]]). Folds on this scale are common within the Bowland Shale, having been formed during the folding of the main Skipton anticline, when bedding-plane slip concentrated movement within the soft and easily deformed shale, which lies between more competent limestone below and gritstone above. This fold is obvious because of the many thin limey bands. Note that the latter are strongly fractured but remain constant in thickness, whilst the intervening shales have been squeezed into the fold axis. This fold strikes northeastwards across the river and flood plain, cropping out for a second time on the opposite side of the meander.
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Walk too m upstream to a point across the river from a small anticline ([[:File:YGS_YORKROCK_FIG_06_02.jpg|Figure 6.2]]). Folds on this scale are common within the Bowland Shale, having been formed during the folding of the main Skipton anticline, when bedding-plane slip concentrated movement within the soft and easily deformed shale, which lies between more competent limestone below and gritstone above. This fold is obvious because of the many thin limey bands. Note that the latter are strongly fractured but remain constant in thickness, whilst the intervening shales have been squeezed into the fold axis. This fold strikes northeastwards across the river and flood plain, cropping out for a second time on the opposite side of the meander.
  
 
==== Locality 4 [SE 076 544] ====
 
==== Locality 4 [SE 076 544] ====
  
Cross the meander along the strike of the fold to the river once again. Here the alternating shales and thin limestones of the Middle Bowland Shale crop out along the near-side of the river. Note that the fold is here observed in horizontal section. Most of the outcrop consists of southeasterly dipping beds, but the angle of dip increases downstream to a point where almost vertical shales are seen to be dipping to the northwest. The vertical shale marks the position of the ford axis. Once again, poorly preserved goniatite fragments may be found. The general absence of '''benthonic''' remains, combined with this distinctive '''lithology''', are indicative of anoxic conditions on the sea bed at the time of accumulation.
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Cross the meander along the strike of the fold to the river once again. Here the alternating shales and thin limestones of the Middle Bowland Shale crop out along the near-side of the river. Note that the fold is here observed in horizontal section. Most of the outcrop consists of southeasterly dipping beds, but the angle of dip increases downstream to a point where almost vertical shales are seen to be dipping to the northwest. The vertical shale marks the position of the ford axis. Once again, poorly preserved goniatite fragments may be found. The general absence of benthonic remains, combined with this distinctive lithology, are indicative of anoxic conditions on the sea bed at the time of accumulation.
  
The view up the Wharfe valley affords an excellent demonstration of river terraces, the most important of which occur at approximately 1.0, 2.5 and 5.0 m above river level.
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The view up the Wharfe valley affords an excellent demonstration of river terraces, the most important of which occur at approximately 1.0, 2.5 and 5.o m above river level.
  
 
==== Locality 5 [SE 078 455] ====
 
==== Locality 5 [SE 078 455] ====
  
Walk upstream for 300 m to a point where the path descends once again to river level. Middle Bowland Shale can be seen cropping out on the opposite side of the river, below the terraces, whilst on the left bank there is a high gritstone cliff. This cliff represents a fault plane, with a spring-line at its base where permeable grit is '''thrown''' against impermeable shale. Here the downthrow side of the fault is the side with the high relief. This is most likely part of the same fault system which was observed at Locality 1, where the downthrow was in the opposite direction.
+
Walk upstream for 300 m to a point where the path descends once again to river level. Middle Bowland Shale can be seen cropping out on the opposite side of the river, below the terraces, whilst on the left bank there is a high gritstone cliff. This cliff represents a fault plane, with a spring-line at its base where permeable grit is thrown against impermeable shale. Here the downthrow side of the fault is the side with the high relief. This is most likely part of the same fault system which was observed at Locality 1, where the downthrow was in the opposite direction.
  
 
==== Locality 6 [SE 078 554] ====
 
==== Locality 6 [SE 078 554] ====

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