Roseberry Topping & Cleveland Dyke

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Roseberry topping is an erosional outlier of the Ravenscar Group on the western edge of the Cleveland escarpment. The area was extensively glaciated and the stratigraphy dips towards the South- Southeast.

The photograph above shows Newton Wood- mostly of Sessile Oak , Ash and Hazel of some age and probably planted on ancient woodland soils. It is noted for its springtime native bluebell and Stitchwort woodland floor plants. It occupies the glacial till overlying the Redcar mudstone formation  described by the BGS as grey fossiliferous, fissile mudstones and siltstones with subordinate thin beds of shelly limestone in lower part, and fine-grained carbonate-cemented sandstone in upper part.

On climbing up through a woodland path we came across bedrock of the Staithes formation shown below. Described as silty sandstone, more or less argillaceous (clay), typically intensely bioturbated and/or showing bedding structures of many types. Bioturbation is defined as the reworking of soils and sediments by animals or plants. These include burrowing, ingestion and defecation of sediment grains. These activities have a profound effect on the environment and are thought to be a primary driver of biodiversity.

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Out of the woodland we emerged onto a bench in the landscape formed by the Cleveland Ironstone formation.OLYMPUS DIGITAL CAMERA This formation of mudstone, silty, argillaceous siltstone and silty sandstone with seams of sideritic and berthierine-ooidal ironstone, occurs typically at the tops of small scale sedimentary cycles. The land here was quite disturbed and hummocky, vegetated with rough pasture and gorse bushes. The rich red colouring  from rabbit burrows shows the presence of red Ochre. Red ochre, Fe2O 3, takes its reddish colour from the mineral hematite, which is an anhydrous iron oxide.

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Although probably mined since prehistoric times Roseberry ironstone mine was commercially founded in the 1870’s and continued until the 1920’s. Underneath Roseberry Topping is a labyrinth of mine workings, some think responsible for the slope collapse visible at the peak. We passed an ancient European Larch tree, a deciduous conifer looked as if it have been growing here for centuries, part of a larger plantation that once flourished here. Larch’s presence in the UK was first mentioned in 1629 and itt soon became a popular plantation tree.

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The track of a mine tramway still exists, stones along the surface showing evidence of many fossils like this one – possibly the bivalve Venericor.

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Lying above the Ironstone formation is the Whitby Mudstone formation of medium and dark grey fossiliferous mudstone and siltstone, laminated and bituminous in part, with thin siltstone or silty mudstone beds and rare fine-grained calcareous sandstone beds; dense, smooth clayey limestone nodules very common at some horizons.  Beds of Grey and Alum shale occur showing up on the grey grey crumbly slopes covered in distinctive brown bracken. Bracken likes dry, slightly acid soils under 450 metres.

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Jet is a type of lignite, a precursor to coal, and is a gemstone. It is derived from wood that has changed under extreme pressure and thin beds occur in the Whitby Formation. Spoil heaps from a Jet mine below the Topping supported different types of plants more typical of Heathland- Heather, bilberry, rich mosses and many lichens such as this cladonia diversa.

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Moorland fungi such as the Moor Club pictured below forms relationships with Heather, thriving amongst the lichen (Cladonia furcata?)

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The Saltwick Formation forms the craggy peak and most of the Cleveland escarpment tops. Consisting of grey mudstone, yellow-grey siltstone and yellow, fine- to coarse-grained sandstone, the sandstones commonly display sharply erosional bases, and channel-fill bedforms. Plant remains and plant rootlets are common in some beds.

The picture below shows thick channel sandstone with some cross-bedding. Although sauropod and stegosaurus footprints have been found in this Middle Jurassic formation, none were visible here.

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The view from the top shows the deltaic beds of the Saltwick formation snaking across the Cleveland hills into the mist.

 

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The Cleveland Dyke is an igneous intrusion which extends from Galloway in southern Scotland through Cumbria and County Durham in northern England to the North York Moors. The dyke is associated with volcanism which took place in the Isle of Mull igneous centre in western Scotland during the early Palaeogene Period. During a time of regional crustal tension associated with the opening of the north Atlantic Ocean,  innumerable dykes were emplaced across the region. It has been extensively quarried along the Langbaugh ridge at Cliff Rigg for roadstone and setts destined for Leeds. Half a mile in length, quarrying began in 1869 and production stopped in 1918 leaving a huge gully in the landscape.

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The treeless gap marks out the course of the dyke as it makes its way to the North Sea.

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This photo shows the elevation of the ridge formed by the Dyke with the dramatic Cleveland hills forming the backdrop.

 

References

Yorkshire Rocks and Landscape: A Field Guide (Rocks & Landscape)  Apr 1994
by Yorkshire Geological Society (Author), Colin Scrutton (Editor)

BGS -Lexicon of named units  BGS

 

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