Editing Carboniferous rocks of upper Nidderdale - an excursion

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=== Locality 4, [SE 0992 7647] ===
 
=== Locality 4, [SE 0992 7647] ===
  
Rejoin the road and turn right briefly, before turning left up the private road to Upper Nidderdale. En route, look right to view the landslip of Thrope Edge, with a steep back scar. Continue northwards past a limestone cliff to the portal of an old railway tunnel, where there is parking [SE 0992 7647]. Descend directly eastwards through the stiles to the River Nidd where the base of the Middle Limestone, resting on mudstone, is seen on the river bed [SE 0994 7639] close to the axis of the Limley '''Anticline'''. The delicate tracery of the compound '''coral''' ''Orionastraea garwoodi ''var ''pristina ''can be observed 1.5 m above the base of the Middle Limestone. About 100 m upstream the River Nidd sinks into Manchester Holes, a depression in the river bed; close by on the east bank a cave entrance is seen in which the roaring waters can be heard. Do not explore this cave since water levels can surge without warning. The waters emerge 3 km downstream, below Lofthouse at Nidd Heads. Extensive underground passages, all in Middle Limestone, and completely water filled near Lofthouse, have been explored.
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Rejoin the road and turn right briefly, before turning left up the private road to Upper Nidderdale. En route, look right to view the landslip of Thrope Edge, with a steep back scar. Continue northwards past a limestone cliff to the portal of an old railway tunnel, where there is parking [SE 0992 7647].
  
Return to the tunnel mouth where in cliffs to the south the greater part of the Middle Limestone is seen '''dipping''' southwards on the southern limb of the Limley Anticline. Just south of the tunnel mouth, 2.4 m of dark grey limestones rich in the large brachiopod ''Gigantoproductus ''are seen close to the axis of the Limley Anticline. The bulk of the fossils are in the original growth position, with the larger, convex (pedicle) valve facing downwards and the concave (brachial) valve acting as a lid. Some 3 m above the top of the ''Gigantoproductus ''beds and immediately beside the eastern wall of the tunnel, scattered specimens occur of the 1 cm long egg-shaped '''blastoid''' ''Orbitremites. ''Higher strata are continuously exposed almost to the top of the Middle Limestone which is here unusually thick and includes the beds seen in the How Stean gorge. These are grey and light-grey limestones, commonly with crinoid debris. There is a further 1 m thick ''Gigantoproductus ''bed, a fossil rarely found at so high a level in the Middle Limestone of the Yorkshire Dales. In contrast the lower band is very extensively developed. A picnic spot is available at the south end of the cliff.
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Descend directly eastwards through the stiles to the River Nidd where the base of the Middle Limestone, resting on mudstone, is seen on the river bed [SE 0994 7639] close to the axis of the Limley Anticline. The delicate tracery of the compound coral ''Orionastraea garwoodi ''var ''pristina ''can be observed 1.5 m above the base of the Middle Limestone. About too m upstream the River Nidd sinks into Manchester Holes, a depression in the river bed; close by on the east bank a cave entrance is seen in which the roaring waters can be heard. Do not explore this cave since water levels can surge without warning. The waters emerge 3 km downstream, below Lofthouse at Nidd Heads. Extensive underground passages, all in Middle Limestone, and completely water filled near Lofthouse, have been explored.
 +
 
 +
Return to the tunnel mouth where in cliffs to the south the greater part of the Middle Limestone is seen dipping southwards on the southern limb of the Limley Anticline. Just south of the tunnel mouth, 2.4 m of dark grey limestones rich in the large brachiopod ''Gigantoproductus ''are seen close to the axis of the Limley Anticline. The bulk of the fossils are in the original growth position, with the larger, convex (pedicle) valve facing downwards and the concave (brachial) valve acting as a lid. Some 3 m above the top of the ''Gigantoproductus ''beds and immediately beside the eastern wall of the tunnel, scattered specimens occur of the 1 cm long egg-shaped blastoid ''Orbitremites. ''Higher strata are continuously exposed almost to the top of the Middle Limestone which is here unusually thick and includes the beds seen in the How Stean gorge. These are grey and light-grey limestones, commonly with crinoid debris. There is a further t m thick ''Gigantoproductus ''bed, a fossil rarely found at so high a level in the Middle Limestone of the Yorkshire Dales. In contrast the lower band is very extensively developed. A picnic spot is available at the south end of the cliff.
  
 
Rejoin the cars and drive up the Nidd Valley almost to Scar House Dam. Park in the visitor car park on the south side of the valley.
 
Rejoin the cars and drive up the Nidd Valley almost to Scar House Dam. Park in the visitor car park on the south side of the valley.

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