Editing Lower and Middle Jurassic rocks between Robin Hood's Bay and Hawsker Bottoms - an excursion

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=== Locality 8 [NZ 960 061] ===
 
=== Locality 8 [NZ 960 061] ===
  
Just past the waterfall and shipwreck remains at Ness Point and just in view of Castle Chamber, look for a particular ironstone nodule bed on the foreshore. This 0.10 m thick composite bed of sideritic nodules has large subvertical burrows in the top, filled with '''chamositic oolitic''' ironstone (the first oolitic ironstone in the Yorkshire Jurassic Basin). Some 9 m above this oolitic horizon is one of several curious ironstone horizons; this one is bimodal in origin with small concretions (0.10 m in diameter) at the top of a 0.20 m concretionary bed.
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Just past the waterfall and shipwreck remains at Ness Point and just in view ofCastle Chamber, look for a particular ironstone nodule bed on the foreshore. This 0.10 m thick composite bed of sideritic nodules has large subvertical burrows in the top, filled with chamositic oolitic ironstone (the first oolitic ironstone in the Yorkshire Jurassic Basin). Some 9 m above this oolitic horizon is one ofseveral curious ironstone horizons; this one is bimodal in origin with small concretions (0.10 m in diameter) at the top of a 0.20 m concretionary bed.
  
From Ness Point on to Castle Chamber large fallen blocks of sandstone from the Staithes Formation may be seen on the foreshore. The stratigraphical top of these blocks often have rippled surfaces and are covered with well-preserved shell debris, including ''Pseudopecten'', ''Protocardia'', ''Gryphaea'', ''Liostrea'' and the '''scaphopod''' ''Dentalium'', the latter often displaying well-developed current orientation. At Bulmer Steel at the base of the cliff and on the foreshore look for a 3.5 m section of grey siltstones with grey nodule horizons where ''Oistoceras figulinum'' might be found (indicating the top Subzone of the ''davoei'' Biozone).
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From Ness Point on to Castle Chamber large fallen blocks of sandstone from the Staithes Formation may be seen on the foreshore. The stratigraphical top of these blocks often have rippled surfaces and are covered with well-preserved shell debris, including ''Pseudopecten'', ''Protocardia'', ''Gryphaea'', ''Liostrea'' and the scaphopod ''Dentalium'', the latter often displaying well-developed current orientation. At Bulmer Steel at the base of the cliff and on the foreshore look for a 3.5 m section of grey siltstones with grey nodule horizons where ''Oistoceras figulinum'' might be found (indicating the top Subzone of the ''davoei'' Biozone).
  
 
=== Locality 9, Castle Chamber [NZ 960 067] ===
 
=== Locality 9, Castle Chamber [NZ 960 067] ===
  
The Ironstone Shales (shales/siltstones) at the top of the Redcar Mudstone Formation grade imperceptibly into the shallow-water siltstones/sandstones of the Staithes Formation. Some 4.5 m below the floor of Castle Chamber is a prominent laminated sandstone, the first real arenaceous horizon of the Staithes Formation. The small sandstone cliff overhang at Castle Chamber provides a good shelter/safety point and the section there forms the biostratigraphical boundary between the Lower and Upper Pliensbachian, with the first ''Amaltheus ''some 0.3 m below the roof sandstones. The '''cross-laminated''' sandstone/siltstone horizons which form the floor and roof of Castle Chamber (usually with oyster beds at the base of both) are exposed on the foreshore between Castle Chamber Point and the Cow and Calf Rocks. Both sandstone units exhibit scour gutters at the base.
+
The Ironstone Shales (shales/siltstones) at the top of the Redcar Mudstone Formation grade imperceptibly into the shallow-water siltstones/sandstones of the Staithes Formation. Some 4.5 m below the floor of Castle Chamber is a prominent laminated sandstone, the first real arenaceous horizon of the Staithes Formation. The small sandstone cliff overhang at Castle Chamber provides a good shelter/safety point and the section there forms the biostratigraphical boundary between the Lower and Upper Pliensbachian, with the first ''Amaltheus ''some 0.3 m below the roof sandstones. The cross-laminated sandstone/siltstone horizons which form the floor and roof of Castle Chamber (usually with oyster beds at the base of both) are exposed on the foreshore between Castle Chamber Point and the Cow and Calf Rocks. Both sandstone units exhibit scour gutters at the base.
  
 
Walking northwest towards Clock Case Nab, you will pass over shallow water sediments, particularly sandstones with nests of ''Protocardia truncata'' (often the centres for sideritic diagenesis). Occasional finds of ''Amaltheus stokesi'' in these sediments indicate the base of the ''margaritatus'' Biozone.
 
Walking northwest towards Clock Case Nab, you will pass over shallow water sediments, particularly sandstones with nests of ''Protocardia truncata'' (often the centres for sideritic diagenesis). Occasional finds of ''Amaltheus stokesi'' in these sediments indicate the base of the ''margaritatus'' Biozone.

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