Humberside Geologist No. 13

Abstracts from joint Yorkshire Geological Society and Hull Geological Society meeting at Hull University. Held on 4th December 2000.

Lectures:

"Management of a karst river: The Lathkill, Derbyshire", by John Gunn from the University of Huddersfield.

The River Lathkill is a very popular tourist destination in the Peak District National Park, England's most visited national park. The upper reach of the river is a Site of Special Scientific Interest and a candidate Special Area of Conservation under the European Union Habitats Directive. It also lies within the Derbyshire Dales National Nature Reserve and includes a Scheduled Ancient Monument, designated for its lead mine remains. The river is a significant and complex hydro-ecological system that is unique in Derbyshire in having no known drainage from non-limestone strata. From its springhead, which migrates up and downstream in response to groundwater levels, the river flows over the surface until a 2 km 'loosing' reach that is totally dry for part of the year. In consequence, the river has a distinct invertebrate community characteristic of ephemeral flow. Below the ephemeral reach the river rises at perennial springs. There is a long history of lead mining in the valley, and oral accounts suggest that
the river was heavily regulated in the nineteenth century. The measures included lining the bed with puddled clay to prevent loss of flow into a lead mine drainage level [sough] that runs beneath the valley floor. It is commonly assumed that the cause of the river drying for variable periods and lengths each year is lack of maintenance of the bed and banks and consequent loss of water to the sough. For ecological, and aesthetic, reasons the site managers are keen to restore perennial flow and research is in progress to determine how this can be achieved. The main focus has been the loosing reach but summer drying has at least a 50 year history and a contributory factor may be the capture of flow from further upstream by other soughs outside the surface catchment. Hence, it is important that any restoration works are placed in the context of the wider karst hydrology.

"Recent cave exploration in Wharfedale", by Brian Judd from Bradford

The eastern side of Wharfedale between Kettlewell and Grassington holds the potential for the longest cave system in Britain. The streams sinking in the area have been an exploration target for cavers for many years revealing over 21 km of passage. The resurgence of the system was first dived over 50 years ago but only over the last few years have divers begun to make significant progress in this complex and demanding cave.

"Studies in Joint Hole, Chapel-le-Dale", by Phil Murphy from the University of Leeds,

Modern cave diving techniques allow direct observation of processes in the phreatic zone whereas in the past studies were limited to relict conduits. The results of research into the sediments, passage morphology and flow dynamics in Joint Hole main passage have produced some intriguing results despite the problems and limitations of working both in a cave and underwater.

'Ryedale Windypits' by Richard Myerscough, from the University of Hull.

The Ryedale Windypits are located in the Hambleton Hills within the North York National Park and have attracted both archaeological and geological interest since the Rev. Buckland first descended 'Buckland's Windypit' in the 1820's .For the last 50 years they have been popular with cavers and now provide important protected bat roosts. The name is derived from cold air rising from the pits with such velocity as to blow out leaves and other debris .The Windypits are vertical fissures in the Upper Jurassic Corallian Group (Lower Calcareous Grit and Coralline Oolite Formations) formed by cambering over the underlying Oxford Clay Formation on scarps and parallel to fault scarps. They differ from the fluvial caves in the Corallian, e.g. Kirkdale. The concentration of Windypits in the Hambleton Hills west of the valley of the River Rye is now seen as stress fracturing associated with a combination of tectonic features and examples from The Cotswolds and Roquefort-sur-Soulzon in Southern France will illustrate the fracturing process associated with their formation.
At least 4 of the Windypits (Antofts , Ashberry, Buckland's and Slip Gill) attracted ancient peoples to use them as ritual burial sites . In The Neolithic Period (Radiocarbon date 1750+/-150bc) Beaker pots with selected animal and human bones /skulls were deposited in the pits. While in Romano-British times (C1st-4th) at least one pit (Ashberry) was used a temple site for ritual sacrifices using animal bones ,metal and other votive objects as sacrifices to the Gods of the Underworld. Parallels are to found in 'Windyholes' of Africa. The historical importance of valley of The River Rye and new Windypits to be discovered by Aerial Photograph survey, Geophysical investigation and excavation supported a recent application to Channel 4 'Time Team'.

Displays:

Gordon Binns and Chris Blackhurst - Fossils collected from the Yorkshire coast and quarries.

"Chalkoholics Anonymous" by Paul Hildreth

The display included: over 200 specimens from the chalk of North Lincolnshire, precise stratigraphical locations of specimens, specimens displayed in stratigraphical order,
photographs and lithostratigraphical logs of sections in North Lincolnshire still available for study and correlation.

'Castleton Limestone Fossils and Blue John Fluorite' by David Hill
Castleton lies at the western end of the Hope Valley in North Derbyshire. It is about 16 miles west of Sheffield and 32 miles east of Manchester.
The limestones around Castleton are of upper Dinantian (Visean) age and were mainly deposited during the Asbian stage (336-339 m.y.). At Treak Cliff the top of the hill is composed of an algal reef and the hill slope, the fore-reef with deeper water shales in the valley at the bottom. Both the algal reef and the fore-reef contain a wide variety of different fossils which tend to be very well preserved.
Before the deposition of the Namurian, uplift occurred and boulders eroded off the reef crest and slid down the fore-reef into the contemporary sea. The Castleton area then resubmerged and Namurian shales and sandstones were deposited on top.
At the end of the Namurian the limestone massif rose and the Edale Gulf continued to subside. These inversion tectonics produced faults into which mineralising fluids rose and deposited lead and zinc ore with fluorite and barite.
At Treak Cliff the mineralisation was almost exclusively of fluorite in the decorative form described as Blue John.

'A new Chalk ammonite from Selwicks Bay' by Mike Horne.

Fossil ammonites in the Yorkshire Chalk are rare. A specimen found in flinty Chalk (Burnham Chalk Formation) on the wave cut platform of Selwicks Bay, Flamborough, East Yorkshire, U.K. has been provisionally identified as Texanites texanus. This is the zonal ammonite for the Lower Santonian. If the identification is correct this ammonites provides evidence that the Coniacian-Santonian boundary is below the base of the flint-less Flamborough Chalk Formation. The fossil also appears to have lappets.

Windy Pits by Scarborough Caving Club.

A general overview of Windy Pits and the areas in which they form, a detailed look into two different Windy Pits (- 'Antofts' and the Club discovery 'Old Fat And Past It Pot') and a quick look at Kirkdale Cave or Bog Hole Rising.

'Echinoid display' by Terry Rockett

A display to show the morphology and characteristics of Echinoids, mainly from the Jurassic and Cretaceous. Several specimens are preserved in flint.

Felix Whitham - A collection of Jurassic and Cretaceous fossils from Yorkshire and North Lincolnshire.

Nigel Whittington - poster display - Caves and caving in Eastern Europe

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In spite of the extensive flooding that occurred that week, in York, Malton, on the A1 and the stopping of most trains, the meeting was attended buy about seventy people. The first half of the meeting was chaired by the Yorkshire Geological Society President, Mike Romano, and the second half was chaired by the Hull Geological Society Vice-President, David Hill. The Society would like to thank Janet Binns, Gordon Binns, Lynden Emery, Ron Harrison and Anne Horne for helping with the refreshments, during the mid-afternoon break, and Mark Anderson, Marion Brazier, Mel Bucknell, Martyn Pedley, Dave Sole, Sue Taylor and Bob Withnell of Hull University for their help in arranging the meeting.

(c) Hull Geological Society 1999 + 2001

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