Humberside Geologist no.10

"The East Yorkshire Boulder Committee"

Report for the years 1987 to 1991

by Ron Harrison and Mike Horne

In the early days of the Hull Geological Society, a committee was formed to record the occurrence of glacial erratic boulders in East Yorkshire. Thousands of these boulders were found and their localities are reported in the Society's Transactions in articles by Thomas Sheppard and J.W.Stather, between 1894 and 1905. Reports were also made to the meetings of the British Association for the Advancement of Science, together with other regional Boulder Committees. When all the reports were put together they formed a large source of data which was used in retracing the paths of the glaciers during the Ice Age.

The Society decided to reform an informal Boulder Committee in 1987 as a contribution to the Society's Centenary celebrations. Richard Myerscough led the first field meeting on the 4th April 1987, to Cowden, Atwick and Barmston. These field meetings have proved to be popular and have become a regular feature of the Society's Summer Programme. Because you never know what will be found, the meetings have a very informal and spontaneous character, and are specially suitable for beginners.

It should be pointed out that the 'East Yorkshire Boulder Committee' is a very loosely used title. No formal Committee exists, it covers areas outside East Yorkshire as well as inside the county and it does not strictly record 'boulders' as it also includes erratic rocks and fossils of any size.

As well as boulders (clasts over 30cm in diameter), smaller erratics have been included. These were not included in the old boulder surveys of the Society and may prove to have interesting distribution patterns. We do not know where some of these smaller erratics have come from, as they are not seen in situ in northern Britain. These include Black Flints which may be of Late Campanian or Maastrichtian age (indicated by microfossils). The fossil belemnite Belemnitella mucronata can be found, and this is of Late Campanian age. Red or reddish brown flints, often with a white outer coating, occur as erratics; Doug Bridger has suggested that these are of Danian (earliest Tertiary) age.

"Rafts" of soft white Chalk can sometimes be seen in the Boulder Clay cliffs or in the clay on the beach at low tide. This chalk is much softer than any found in situ in Yorkshire and has a putty-like texture. 1t is sometimes associated with the Black Flints and Belemnitella mucronata (but these may not be from the Chalk). Microfossils from these Chalk rafts are of Late Campanian to Early Maastrichtian age; younger than Yorkshire Chalk.

"Rafts" of red clay can also be seen. These were originally thought to be Red Chalk but recent study of microfossils from some of these rafts has shown a Cenozoic age. In the light of this new dating, rafts of grey clay previously assumed to be Speeton Clay or of Jurassic age should be studied more closely.


PALAEOCENE - Red Flint,? Clay 'Rafts'

CRETACEOUS - Speeton Clay Fossils,

Chalk, Flints (Grey, Black, Brown)

JURASSIC - Shales, Sandstones,

Limestones, Bi-Valves, Ammonites, Belemnites.

TRIASSIC - Red Sandstones

PERMIAN - Magnesian Limestone, Brockram.


DEVONIAN - Old Red Sandstone


LAKE DISTRICT - Shap Granite


SCANDINAVIA - Larvikite, Rhomb-porphyry


IGNEOUS ROOKS - Graphite, Porphyritic Dyke Rocks, Dolerite, Basalt.

METAMORPHIC ROCKS - Gneisses, Schists

SEDIMENTARY ROCKS - Various Sandstones, Limestones & Shales, Pyrites, Coal Fragments, etc.

Geological Time Scale in Millions of Years























































As these late Cretaceous and early Tertiary rocks and fossils are not found onshore in northern Britain, they have probably come from the bed of the North Sea, scraped up by the glaciers during the Ice Age.

The occurrence of other sub-boulder fossils was also ignored by the previous Committee and some of them may have interesting patterns of distribution. Speeton Clay belemnites are common at some localities (for example, all the zonal belemnites have been found at Hornsea), but are not found at others. Their distribution may reveal whether they have an on-shore or off-shore origin. But more details are needed before we can decide.

The Jurassic oyster Gryphaea occurs nearly everywhere and is very robust. Middle Jurassic sandstones can be found, often with rootlets in them, and occasionally delicate fossilised leaves are preserved, showing that the ice is not always destructive. Carboniferous Limestone is fairly common, often in rounded clasts which are marked with scratches. The Carboniferous coral Lithostrotian is very distinctive.

This report does not mark the end of the Boulder Committee. It is hoped that the Society erratic field meetings will continue and that members will continue to pass on records of the erratics they have found. Hopefully we can write another report in a few years time, filling in some of the gaps in the records and perhaps coming to some conclusions from the distribution patterns.

This report is based on notes made at the Society's special Boulder Committee field meetings and records contributed by individual members. We would like to thank everyone who has taken part for their contributions. We will list each locality visited in turn (in a clock wise order) and then note all the erratics recorded so far:

Cayton Bay (Waterworks) : (Boulders) Shap Granite, veined Dolerite, Carboniferous Limestone.

Cayton Bay : Shap Granite, Dolerite, Jasper, Carboniferous Limestone, Brockram.

Filey Brigg : ice scratched Carboniferous Limestone, Syringopora, Brockram, Cannon Ball Limestone, Gryphaea, ammonite, Dogger, jasper.

South of Filey : large boulder of Shap Granite.

Speeton : granite, Rhomb Porphyry, basalt , volcanic breccia, folded gneiss, quartz, jet, Carboniferous Limestone, Lithostrotian, red sandstone, Gryphaea, Liassic limestone, Deltaic Sandstone with rootlets, Chalk, flint, black flint.

Thornwick Bay : granite, basalt, jasper, Carboniferous Limestone.

Stottle Bank (North of Selwicks Bay) : Shap Granite, red microgranite, coarse grained granite, diorite, vesicular basalt, volcanic breccia, Carboniferous Limestone, Lithostrotian, Deltaic Sandstone, septarian nodules.

Selwicks Bay : Deltaic Sandstone with rootlets, septarian nodules.

High Stacks : large Shap Granite, dolerite, coarse grained granite, Rhomb Porphyry, basalt, Larvikite (common), gneiss, red micaceous sandstone, Carboniferous Limestone with corals, crinoids and Productids, coal, Deltaic Sandstone, black flint.

South Landing : Shap Granite, Larvikite, granite, ? Whin Sill, porphyry, basalt, augen gneiss, quartzite, Lithostrotian, Carboniferous Limestone, Brockram, ripple-marked Jurassic sandstone, Deltaic Sandstone, Corallian stromatolitic limestone, septarian nodule (? Kimmeridgian from Speeton), black flint.

Sewerby Steps : Shap Granite (large), Rhomb Porphyry, granite, gabbro, basalt (large) folded garnet gneiss, mica schist, Carboniferous Limestone, Lithostrotian, Brockram, red sandstone, Gryphaea, shelly Jurassic limestone, Deltaic Sandstone with rootlets, septarian nodules, flint.

Barmston : granite, dolerite, red amygdaloidal andesite, Rhomb Porphyry, basalt, tuff from the Borrowdale Volcanics, gneiss, meta-quartzite, orth-quartzite, ice-scratched Carboniferous Limestone, Lithostrotian, red sandstone, Brockram, Magnesian Limestone, Deltaic Sandstone, septarian nodule, Chalky black flint, red flint.

Skipsea : granite, Rhomb Porphyry, dolerite, basalt, vesicular basalt, gneiss, schist, slate, meta-quartzite, jasper, Old Red Sandstone, ice scratched Carboniferous Limestone, Lithostrotian, Brockram, Jurassic shelly limestone, Hildoceras bifrons, septarian nodule, Cementstone from Speeton Clay, Deltaic Sandstone, Chalk, grey flint with Chondrites, brown flint, black flint, red flint.

Atwick : Shap Granite, black porphyry, red porphyry, granite, Whin Sill, basalt, vesicular basalt, ? pillow lava, gneiss, garnet gneiss, jasper, phyllite, crinoidal Carboniferous Limestone, Lithostrotian, red sandstone, Old Red Sandstone, Brockram, Liassic limestone, Gryphaea, Dactylioceras, septarian nodule, Deltaic Sandstone, ? Speeton Clay, ammonite from Speeton Clay, Chalk, Cremnoceramus deformis in grey flint, black flint, Belemnitella mucronata, red flint.

Hornsea : granite, basalt, schist, garnet gneiss, Liassic limestone, Deltaic Sandstone with rootlets, Echinocorys in flint.

Hornsea to Mappleton : granite, Rhomb Porphyry, granite with xenoliths, basalt (some large), Larvikite, augen gneiss, folded gneiss, gneiss, folded schist, chlorite schist, garnet mica schist, jasper, vein quartz, Carboniferous Limestone (some large), Lithostrotian, Brockram, coal, Cannon Ball Limestone, mottled Bunter Sandstone, Gryphaea, Pentacrinus, Promicroceras, Arnioceras, Hildoceras, Pleuroceras, Harpoceras, Dactylioceras, Nautilus, Deltaic Sandstone with rootlets, Cardinia, phosphatic nodules from the Speeton Clay, Exogyra, Aetostreon, Acroteuthis, Oxyteuthis, Hibolites, Neohibolites, Chalk, grey flint, Echinocorys in flint, Chondrites in Chalk, black flint, Belemnitella mucronata, red flint.

Cowden : Shap Granite, Larvikite, basalt, migmatite, Rhomb Porphyry, augen gneiss, jasper, agate, Carboniferous Limestone, Lithosrotian, Brockram, Bunter Sandstone, Liassic limestone, septarian nodules, ripple-marked Deltaic Sandstone, phosphatic nodule from Speeton Clay, Chalk, black flirt.

Aldborough : pink granite, Rhomb Porphyry, basalt, vesicular basalt, gneiss, garnet gneiss, vein quartz, brown micaceous sandstone, green micaceous sandstone, Lithostrotian, Liassic limestone, Gryphaea, Jurassic belemnites, Jurassic mudstone, Dogger, phosphagic nodule, Chalk, grey flint, black flint, red flint, coal.

Easington : Larvikite.

Kilnsea : pink Peterhead Granite, Dalbeatie Granite, dolerite, pink granite, Larvikite, grey granite, black porphyry, basalt, quartz porphyry, Borrowdale volcanics, serpentinite, jasper, meta-quartzite, vein quartz, carnelian, pyrite, greywacke, gneiss, Lithostrotian, coal, Brockram, Cannon Ball Limestone, Bunter Sandstone, red sandstone, Liassic ammonites, Hildoceras bifrons, Dactylioceras tenuicostatum, Gryphaea, Pentacrinus, Deltaic Sandstone with plant fossils, Chalk, chalk concrete, black flint, Belemnitella mucronata, septarian nodules.

Spurn (beach near Information Centre) : Shap Granite, Rhomb Porphyry, quartz jasper, Carboniferous Limestone with corals, Gryphaea.

Spurn Point : red granite, grey granite, red microgranite, porphyry, Larvikite, basalt, gneiss, sandstone, ironstone, Deltaic Sandstone, Gryphaea, Dactylioceras, Chalk, Inoceramus, grey flint.

Paull and Thorngumbald : Lighthouse no erratics; all material recently dumped.

Hessle : Rhomb Porphyry, basalt, red granite, meta-quartzite, sandstone Lithostrotian, Gryphaea, Inoceramus, grey flint, brown flint.

North Ferriby : Rhomb Porphyry, gabbro, basalt, gneiss, garnet schist, sandstone, ice scratched Carboniferous Limestone, Gryphaea, Exogyra, Acroteuthis, Chalk, black flint, Belemnitella mucronata, red flint.

South Ferriby : grey sandstone. Liassic limestone.

Brandesburton Gravel Pit : pink granite, grey granite, dolerite, Larvikite, Rhomb Porphyry, basalt, gneiss, quartzite, jasper, green sandstone, Carboniferous Limestone with corals, Lithostrotian, paper shale, Gryphea, Cardinia, Deltaic Sandstone, Chalk, grey flint, black flint.

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