Editing Carboniferous rocks of the Howick shore section - an excursion

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Walk northwards along the cliff-top path past the Bathing House, seeing Dunstanburgh Castle in the far distance. The low cliffs here are of the channel sandstone with conspicuous cross-bedding. From above Howick Bay there is a fine view towards Cullernose Point, streaked white by the nesting birds. In the near distance about 200 m ahead, the Howick Fault runs east–west across the foreshore. The main feature seen from this viewpoint is the northern end of the major fluvial channel ([[:File:YGS_NORTROCK_FIG_07_2.jpg|Figure 7.2]]), ([[:File:YGS_NORTROCK_FIG_07_3.jpg|Figure 7.3]]). At low tide, look down and seawards across the foreshore exposures to see the basal erosion surface of the channel rise stratigraphically towards the north. There is a conspicuous bed of sandstone (a seatearth) at the top of the channel infill which can be followed south and then southeastwards out to sea as a result of a small synclinal structure. The sandstone within the channel shows bedding surfaces dipping gently towards the south, the result of lateral accretion of the channel margin. Again the channel cuts down to within a metre of the Howick Limestone (which crops out along the far side of a small inlet). A little farther north, the same succession as at Howick Haven can be seen, where the channel sandstone is absent. Overall, this and the last two localities together clearly demonstrate the discrete, localized nature of a major downcutting channel into the marine shales above the Howick Limestone. It suggests that there was a major change in base-level, which may have been the result of a large fall in relative sea-level.
 
Walk northwards along the cliff-top path past the Bathing House, seeing Dunstanburgh Castle in the far distance. The low cliffs here are of the channel sandstone with conspicuous cross-bedding. From above Howick Bay there is a fine view towards Cullernose Point, streaked white by the nesting birds. In the near distance about 200 m ahead, the Howick Fault runs east–west across the foreshore. The main feature seen from this viewpoint is the northern end of the major fluvial channel ([[:File:YGS_NORTROCK_FIG_07_2.jpg|Figure 7.2]]), ([[:File:YGS_NORTROCK_FIG_07_3.jpg|Figure 7.3]]). At low tide, look down and seawards across the foreshore exposures to see the basal erosion surface of the channel rise stratigraphically towards the north. There is a conspicuous bed of sandstone (a seatearth) at the top of the channel infill which can be followed south and then southeastwards out to sea as a result of a small synclinal structure. The sandstone within the channel shows bedding surfaces dipping gently towards the south, the result of lateral accretion of the channel margin. Again the channel cuts down to within a metre of the Howick Limestone (which crops out along the far side of a small inlet). A little farther north, the same succession as at Howick Haven can be seen, where the channel sandstone is absent. Overall, this and the last two localities together clearly demonstrate the discrete, localized nature of a major downcutting channel into the marine shales above the Howick Limestone. It suggests that there was a major change in base-level, which may have been the result of a large fall in relative sea-level.
  
=== Locality 9 [NU 259 179] ===
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''Locality 9 [NU 259 179]''. Descend to the southeast corner of Howick Bay where the remains of amphibian footprints can be seen on the hummocky surface of a sandstone bed 20 cm below a prominent thin coal seam at the base of the east–west running cliff (Scarboro & Tucker 1995). These footprints, averaging 18 cm in length and 14 cm in width, are now poorly preserved, but it should be possible to discern a trackway of 6 prints, 3 each side, with a central groove where the body was dragged through the sand. In the better preserved footprints, 5 digits could be distinguished and some have a mud rim. The sand became vegetated and penetrated by numerous rootlets and ''Stigmaria ''which disturbed the footprint surface and account for its hummocky nature. The footprints, probably formed by a temnospondyl amphibian crawling out onto damp sand from a nearby embayment or lake, were preserved by the deposition of a thin sheet of sand over the surface, probably from the flooding of a small channel. They are some of the oldest footprints in Britain.
Descend to the southeast corner of Howick Bay where the remains of amphibian footprints can be seen on the hummocky surface of a sandstone bed 20 cm below a prominent thin coal seam at the base of the east–west running cliff (Scarboro & Tucker 1995). These footprints, averaging 18 cm in length and 14 cm in width, are now poorly preserved, but it should be possible to discern a trackway of 6 prints, 3 each side, with a central groove where the body was dragged through the sand. In the better preserved footprints, 5 digits could be distinguished and some have a mud rim. The sand became vegetated and penetrated by numerous rootlets and ''Stigmaria ''which disturbed the footprint surface and account for its hummocky nature. The footprints, probably formed by a temnospondyl amphibian crawling out onto damp sand from a nearby embayment or lake, were preserved by the deposition of a thin sheet of sand over the surface, probably from the flooding of a small channel. They are some of the oldest footprints in Britain.
 
  
 
In the north–south running cliff in the corner of the bay, two channel structures show lateral accretion ([[:File:YGS_NORTROCK_FIG_07_4.jpg|Figure 7.4]]). In the cliff on the right (to the north) a 1.5 m thick mudrock to fine sandstone coarsening upward unit can be seen which, in the central part of the cliff, is cut by a shallow channel filled with sandstone showing inclined bedding to the south. These dipping surfaces are produced by lateral accretion (meandering) of the channel. This small channel is then cut into by a larger channel to the left ([[:File:YGS_NORTROCK_FIG_07_4.jpg|Figure 7.4]]). This arrangement has been interpreted as levee sediments (the coarsening-upward unit) cut into by a crevasse channel, and then the main distributary channel taking the path of the crevasse channel (Elliott, 1976).
 
In the north–south running cliff in the corner of the bay, two channel structures show lateral accretion ([[:File:YGS_NORTROCK_FIG_07_4.jpg|Figure 7.4]]). In the cliff on the right (to the north) a 1.5 m thick mudrock to fine sandstone coarsening upward unit can be seen which, in the central part of the cliff, is cut by a shallow channel filled with sandstone showing inclined bedding to the south. These dipping surfaces are produced by lateral accretion (meandering) of the channel. This small channel is then cut into by a larger channel to the left ([[:File:YGS_NORTROCK_FIG_07_4.jpg|Figure 7.4]]). This arrangement has been interpreted as levee sediments (the coarsening-upward unit) cut into by a crevasse channel, and then the main distributary channel taking the path of the crevasse channel (Elliott, 1976).

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