Editing Lower Jurassic rocks between Staithes and Port Mulgrave - an excursion

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At the first headland, Penny Nab, scattered ironstone concretions occur in shales a few metres from the cliff at the base of the Cleveland Ironstone Formation. With the change in '''lithology''', there is a reduction in '''benthonic''' fauna and an increase in '''pelagic''' fauna, principally belemnites and ammonites. It is possible to find species of the ammonite ''Amaltheus ''around here. Some of the ironstone concretions contain a rich fauna of bivalves with '''brachiopods''' and small ammonites. Immediately beyond the headland, there is an excellent view to the southeast, across the wide wave-cut platform of Jet Wyke. The Cleveland Ironstone Formation is superbly exposed in the cliffs and on the foreshore, with the ironstone bands standing out as thin, more resistant, orangey-brown units. The succession of bands, from the Avicula Seam to the Main Seam, can be readily identified in the cliff section ([[:File:YGS_YORKROCK_FIG_16_02.jpg|Figure 16.2]], [[:File:YGS_YORKROCK_FIG_16_03.jpg|Figure 16.3]]).
 
At the first headland, Penny Nab, scattered ironstone concretions occur in shales a few metres from the cliff at the base of the Cleveland Ironstone Formation. With the change in '''lithology''', there is a reduction in '''benthonic''' fauna and an increase in '''pelagic''' fauna, principally belemnites and ammonites. It is possible to find species of the ammonite ''Amaltheus ''around here. Some of the ironstone concretions contain a rich fauna of bivalves with '''brachiopods''' and small ammonites. Immediately beyond the headland, there is an excellent view to the southeast, across the wide wave-cut platform of Jet Wyke. The Cleveland Ironstone Formation is superbly exposed in the cliffs and on the foreshore, with the ironstone bands standing out as thin, more resistant, orangey-brown units. The succession of bands, from the Avicula Seam to the Main Seam, can be readily identified in the cliff section ([[:File:YGS_YORKROCK_FIG_16_02.jpg|Figure 16.2]], [[:File:YGS_YORKROCK_FIG_16_03.jpg|Figure 16.3]]).
  
Cross Jet Wyke towards the next headland of Old Nab. On the traverse, scattered ammonites and belemnites can be found in the shales. The effects of the minor faults which cut the succession can best be seen where they displace the ironstones, whose detailed character can be examined in several places, preferably on the foreshore well away from the base of the cliffs. The Avicula Seam, for example, which is repeated on the foreshore by the faulting, shows an irregular top, with specimens of ''Oxytoma cygnipes ''(formerly ''Avicula) ''and other bivalves, burrows formed by ''Protocardia, ''and a '''conglomeratic''' base. The rock is a fine-grained sideritic mudstone, containing pale green ooliths of chamosite which are best seen on fresher surfaces.
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Cross Jet Wyke towards the next headland of Old Nab. On the traverse, scattered ammonites and belemnites can be found in the shales. The effects of the minor faults which cut the succession can best be seen where they displace the ironstones, whose detailed character can be examined in several places, preferably on the foreshore well away from the base of the cliffs. The Avicula Seam, for example, which is repeated on the foreshore by the faulting, shows an irregular top, with specimens of ''Oxytoma cygnipes ''(formerly ''Avicula) ''and other bivalves, burrows formed by ''Protocardia, ''and a '''conglomeratic''' base. The rock is a fine-grained sideritic mudstoile, containing pale green ooliths of chamosite which are best seen on fresher surfaces.
  
 
=== Locality 3 [NZ 794 188] ===
 
=== Locality 3 [NZ 794 188] ===

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