Editing Chalk of Flamborough Head - an excursion

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=== Locality 2, Danes Dyke [TA 231 692] ===
 
=== Locality 2, Danes Dyke [TA 231 692] ===
  
Flamborough Chalk Formation (Danes Dyke Member), ''Marsupites testudinarius ''(26 m) and ''Uintacrinus socialis'' (29 m) Biozones. There is a car park on the site of Danes Dyke House (with toilets and a small refreshment shop in summer). Walk through the woods to the beach noting the Iron Age earthwork which cuts across Flamborough Head to isolate its eastern end. The dyke is a deep ravine, now occupied by a small seasonal stream cutting into glacial deposits that filled a much larger glacial '''spillway'''. The ravine is cut along the Danes Dyke Fault that can be seen as highly fractured and contorted chalk in the cliff section to the west of the drainage pipe. Glacial deposits rest on the planed surface of the chalk. The fault can sometimes be traced across the beach in winter after severe storms have swept the beach clear of sand.
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Flamborough Chalk Formation (Danes Dyke Member), ''Marsupites testudinarius ''(26 m) and ''Uintacrinus socialis'' (29 m) Biozones. There is a car park on the site of Danes Dyke House (with toilets and a small refreshment shop in summer). Walk through the woods to the beach noting the Iron Age earthwork which cuts across Flamborough Head to isolate its eastern end. The dyke is a deep ravine, now occupied by a small seasonal stream cutting into glacial deposits that filled a much larger glacial spillway. The ravine is cut along the Danes Dyke Fault that can be seen as highly fractured and contorted chalk in the cliff section to the west of the drainage pipe. Glacial deposits rest on the planed surface of the chalk. The fault can sometimes be traced across the beach in winter after severe storms have swept the beach clear of sand.
  
Walking west, the southerly dip brings down the upper part of the ''Marsupites testudinarius ''Biozone for about 200 m to a prominent group of four boulders on the beach. The thinly bedded, flintless marly chalk is full of the isolated calyx plates (see '''crinoid''') of the index fossil, and their density increases upwards through the zone, with complete examples of the stemless calyxes not uncommon, especially along marl bands. Other fossils include echinoids, '''belemnites''', brachiopods, and starfish ossicles from faecal pellets.
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Walking west, the southerly dip brings down the upper part of the ''Marsupites testudinarius ''Biozone for about 200 m to a prominent group of four boulders on the beach. The thinly bedded, flintless marly chalk is full of the isolated calyx plates (see crinoid) of the index fossil, and their density increases upwards through the zone, with complete examples of the stemless calyxes not uncommon, especially along marl bands. Other fossils include echinoids, belemnites, brachiopods, and starfish ossicles from faecal pellets.
  
From Danes Dyke return to the car park or the coastal path, or else, '''but only on a falling tide''', cross the Danes Dyke fault, which throws down to the south, and follow the shoreline eastwards out of the bay for 500 m to Hartendale Gutter [TA 221 692]. For about 200 m the more massive-bedded chalk, with bedding plane '''stylolites''' formed by loading and solution, is cut in the ''Marsupites testudinarius ''Biozone, but on approaching Hartendale Gutter, the calyx plates become fewer and the succession passes into the ''Uintacrinus socialis ''Biozone. This stemless crinoid is present locally and may have been (like ''Marsupites) ''a deeper-water species swept into the Northern Province, as these two fossils are common at this horizon throughout England. The section at Hartendale Gutter is one of the few British localities for complete specimens, but more commonly they are found as isolated calyx plates or groups of plates and arm ossicles, indicating individuals falling into quiet conditions on the sea floor. Other fossils found include echinoids, brachiopods, '''corals''', belemnites and sponges.
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From Danes Dyke return to the car park or the coastal path, or else, '''but only on a falling tide''', cross the Danes Dyke fault, which throws down to the south, and follow the shoreline eastwards out of the bay for 500 m to Hartendale Gutter [TA 221 692]. For about 200 m the more massive-bedded chalk, with bedding plane stylolites formed by loading and solution, is cut in the ''Marsupites testudinarius ''Biozone, but on approaching Hartendale Gutter, the calyx plates become fewer and the succession passes into the ''Uintacrinus socialis ''Biozone. This stemless crinoid is present locally and may have been (like ''Marsupites) ''a deeper-water species swept into the Northern Province, as these two fossils are common at this horizon throughout England. The section at Hartendale Gutter is one of the few British localities for complete specimens, but more commonly they are found as isolated calyx plates or groups of plates and arm ossicles, indicating individuals falling into quiet conditions on the sea floor. Other fossils found include echinoids, brachiopods, corals, belemnites and sponges.
  
 
Return to Danes Dyke, or continue east to South Landing via the coastal path or beach (only on a falling tide.)
 
Return to Danes Dyke, or continue east to South Landing via the coastal path or beach (only on a falling tide.)

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