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A list of glacial erratics found on field meetings of the Hull Geological Society or records contributed by members.

In the early days of the Society there was a "Boulder Committee" which recorded erratics in East Yorkshire and published the details. Other Societies did similar work and this led to a greater understanding of the directions of ice movement during the Ice Age. The "Boulder Committee" was revived for the Society's centenary in 1988 and a report published (Harrison and Horne 1992), which lists erratics found and gives further details of the survey. We have continued to hold special Boulder field meetings, which are an excellent introduction to local geology for beginners and also have recorded erratics on other meetings.

There has been an increasing number of human-influenced erratics on the coast with the use of exotic rocks for sea defences. These get broken up and washed along the coast by longshore drift, and soon these become rounded and hard to distinguish from true glacial erratics. So we also record here the siting of these rocks so that future generations of geologists will be aware of this human interference:

Barmston: Oolitic limestone

Hornsea: Carboniferous limestone, larvikite, augen gneiss.

Mappleton: a variety of gneisses, igneous rocks including pegmatites.

Withernsea: Larvikite (Blue Pearl variety)

Dimlington: Larvikite (Blue Pearl and Emerald Pearl varieties some pegmatitic)

Spurn: limestones and concrete.

Garnet muscovite schist, chalk, black flint, rhomb porphyry, metaquartzite, Gryphaea, vein quartz, jasper, red sandstone, chlorite schist, cementstone nodules, Old Red Sandstone.

Crinoidal Carboniferous Limestone, Dolerite, Shap Granite, Gryphaea, Lithostrotion, conglomerate, basalt, jasper, vein quartz, black porphyry.

Larvikite, black flint, red granite, Gryphaea, Ice scratched Carboniferous limestone, Lithostrotion, rhomb porphyry, biotite gniess, Middle Jurassic Sandstone,

Liassic ammonites, light and dark larvikite (note a lot of larvikite has been imported for the sea defences at the gas terminal), black flint, red quartz conglomerate, rhomb porphyry, granite, red amygdaloidal lava, Lithostrotion, gneiss, grey granite, white quartz, sandstone, greywacke, Liassic fossil wood, biotite schist, Gryphaea (rare), jasper, red flint, Belemnitella, chalk, Middle Jurassic plant-bed and coal, Jurassic septarian nodule, brown flint, Kimmeridge Septarian nodule, Red Chalk with Neohibilites, Brockram, Permian Cannon-ball limestone, basalt, ?Kimmeridge Clay, serpentinite, pyrite, Tilberthwaite Tuff, yellow quartz, carboniferous crinoidal limestone.

Larvikite, red granite, pink granite, Jurassic sandstone, gneiss, garnet schist, gabbro, brockram, red flint, black flint, rhomb porphyry, Lithostrotion, Carboniferous limestone, jasper, cement stones from the Speeton Clay, brown septarian nodules, Jurassic plants, basalt, chalk, serpentinite, vein quartz, crinoidal Carboniferous limestone, carnelian. [note: no belemnites, Gryphaea, Shap Granite.]

Chalk, black flint, rhomb porphyry, pink granite, gneiss, larvikite, Gryphaea, micaceous sandstone, quartzite, shelly Jurassic Limestone, crinoidal Carboniferous limestone, red flint, red sandstone, vein quartz, Jurassic deltaic sandstone, Greywacke (Lake District).

Chalk, Carboniferous limestone, Pecten, Deltaic sandstone, schist, Permian sandstone, black flint, Gryphaea, granite, red flint, basalt, rhomb porphyry, Magnesian Limestone, Inoceramus lingua, Whin Sill, Jurassic cementstone, biotite gneiss, Brockram, jet, coal, jasper.

Red flint, Black flint, serpintinite, Liassic ammonites, rhomb porphyry, crinoidal Carboniferous limestone, Lithostrotion, gneiss, white vein quartz, red sandstone, chalk, Gryphaea, septarian nodules, jasper, Deltaic sandstone rootlet bed, granite, coal, Pentacrinus, Jurassic belemnite, Arnioceras, Cardinia, Nanobelus, agate, Hibolites, Exogyra from Speeton Clay, Kimmeridge shales and ammonites, grey flint, larvikite, Inoceramus, Breccia, Dactylioceras, gabbro, garnet Gniess, basalt, Dacromya [Nuculana] ovum, onyx, opal, spotted slate, greywacke, Pseudomytiloides, Brockram, biotite schist, Carboniferous corals, yellow quartz, Galerites in black flint, Speeton Clay nodules, Echinocorys in grey flint, Belemnitella, jet, Red Chalk, Pentacrinus, pyrite, Acroteuthis, mudstone with ostracods.

Note: sea defences of augen gneiss and larvikite.

Rhomb porphyry, black flint, chalk, Gryphaea, ammonites, bored chalk pebbles, red microgranite, gneiss, red flint, septarian nodules, granite, red sandstone Whin Sill, Carboniferous limestone, Jurassic coal, jet, pink granite, Deltaic sandstone rootlet bed, Larvikite, Jurassic belemnite, Mortoniceras (lower Chalk ammonite), sponge in black flint, Cardinia, basalt, biotite schist, grey porphyry, Lithostrotion, brown flint, Belemnitella, Rhynchonella, Jurassic coral, Hemiaster, Echinocorys, greywacke, Arnioceras, Penrith sandstone, Jurassic serpulid, Kimmeridge shale, Micraster, Brockram, coal, quartz, red porphyry, jasper, Calamites, Phylloceras, mica schist, burrow flints, pegmatite, Hippododium.

Coal, chalk, Carboniferous Limestone, grey flint, black flint, Gryphaea, Lithostrotion, pink granite, grey granite, quartzite, ammonites, belemnites from the Speeton Clay, Belemnitella.

Jurassic belemnites, Jurassic coal, ice scratched septarian nodules, Hibolites, coal, Gryphaea, jasper, Red Chalk, Oxyteuthis, Kimmeridge Clay cementstone, chalk, Hildoceras bifrons, Kimmeridge Clay, Neohibolites, Acroteuthis, Exogyra, black flint, granite, Carboniferous corals and crinoids, Pentacrinus, Dactylioceras, basalt, chalk, pyrite, pink chalk, shelly Jurassic limestone, brown sandstone, mudstone, Deltaic rootlet bed, vein quartz, brown sandstone, rhomb porphyry, Crioceratid ammonite (Speeton Clay), jasper, Lithostrotion, larvikite, quartzite, green jasper, Cannon Ball limestone, Speeton Clay nodules, ?tufa, gneiss.

Gryphaea, Belemnitella, Speeton Clay belemnites, rhomb porphyry, granite, gneiss, coal, Echinocorys in chalk, Liassic ammonite, red flint, Lithostrotion, black flint, quartz, Acroteuthis, Carboniferous Limestone with ice scratches, Endemoceras, schist, Oxyteuthis, Hibolites, Neohibolites.

Old Red Sandstone,

Basalt, Lithostrotion, brown sandstone, Old Red Sandstone, Shap Granite, Jurassic oyster bed, Gryphaea, amber

Septarian nodules, jasper, Carboniferous Limestone with brachiopods, gniess, Lithostrotion, black flint (common), basalt, granite, Old Red Sandstone, gniess, Jurassic ammonite, Dogger, Belemnitella.

Large boulders of Basalt, gabbro, Shap Granite, grey gneiss, Peterhead Granite.

Smaller boulders and pebbles of: Black flint, red flint, basalt, rhomb porphyry, shelly Jurassic limestone, granite, Old Red Sandstone, brown sandstone, Middle Jurassic sandstone, yellow quartz, grey flint, grey rhomb porphyry, jasper, larvikite, Dogger, red/brown quartzite, Harpoceras, gabbro, coal, shale, Lithostrotion, crinoidal Carboniferous Limestone, metaquartzite.

Basalt, quartzite, Dogger, gniess, Larvikite, black flint, Lower Jurassic Limestone, red and grey porphyry, grey flint, crinoidal Carboniferous Limestone, yellow quartz, Gryphaea.

Dactylioceras, Gryphaea, Cardinia, Black Cheviot Porphyry, Brockram, gniess, yellow quartz, basalt,

Spurn Point:

Black flint, red flint, Gniess, Echinocorys in black flint, Granite, red and black rhomb porphyries, sandstone, garnet Gniess, biotite gneiss, Lithostrotion, white vein quartz, red sandstone, white quartzite, red sandstone, septarian nodule, grey flint, chalk, greywacke, garnet schist, jasper, Gryphaea in shelly limestone, Harpoceras, basalt, green sandstone, Belemnitella, red breccia, Shap Granite, larvikite, Astarte, Jurassic belemnite, Favosites, Brockram.

Dactylioceras, jasper, chalk, coal, yellow, milky and rosy quartz, Deltaic plant bed, black flint, red sandstone, septarian nodules, Jurassic belemnite, Jurassic ammonite, grey granite, Gryphaea. Grey shale, Lithostrotion, Jurassic shelly limestone, pyrite, Arnioceras, larvikite, gneiss, red porphyry, Red Chalk, basalt, Amaltheus, crinoidal Carboniferous limestone, serpentinite, Pentacrinus, red flint, greywacke, Cardinia, Belemnitella, Asteroceras, Cuspiteuthis, Tilbertwaite Tuff, jasper, black Cheviot porphyry, grey flint, Old Red Sandstone, Middle Jurassic rootlet bed, coal, Hildoceras, Arnioceras.

Compiled by M Horne from records of Hull Geological Society field meetings and own observations, with contributions by Nigel Whittington.

References:

Harrison R & Horne M 1992. The East Yorkshire Boulder Committee, report for the years 1987 to 1991. Humberside Geologist 10, 18-22.

Horne M 1992. Starting Geology in East Yorkshire. Humberside Geologist 10, 13.

Rockett T 1992. Glaciation and the Yorkshire Coast. Humberside Geologist 10, 14.

Published in Humberside Geologist no. 13, 2000.