The Hollybush Sandstone, locally referred to as the "Greensand" or "Greenstone", is a Cambrian aged geologic formation in the Malvern Hills of Worcestershire. It is primarily composed of sandstones, and contains a sparse record of shelly fossils.
Geology The Hollybush Sandstone, which is unconformably overlain by the White Leaved Oak Shale, and underlain by the Malvern Quartzite, is primarily composed of soft, fine-grained micaceous sandstone, which is notably pale olive-green in colouration, giving the formation its local names of "Greensand" and "Greenstone". The sandstone is noted to weather quickly, turning a distinctive brownish colour, primarily due to the presence of hydrated ferric oxides, alongside occasional manganese oxides which form visible black bands along bedding-planes within the rock. There is also a presence of detrital muscovite, with the primary rocks noted to be studded with the minerals.
At other localities, such as in Winter Combe, the rock is noted to be more shaly to loosely cemented in nature, with a brown to dull-green colouration, which weathers to a rich brown. This has been compared to highly ferruginous sandstones.
Dating Whilst it has not been properly dated, the Hollybush Sandstone has been correlated to other formations across Avalonia, including being correlated to the roughly the middle of the Swithland Formation in Leicestershire, the Purely Shale in Nuneaton, the Brigus Formation in Newfoundland, and the Pen-y-Bryn Grit, the Motted Blue Slates, and Green Slates of Nantlle in North Wales. This roughly sees it dated to somewhere between 530 – , or Stage 2 of the Cambrian.
Paleobiota The Hollybush Sandstone contains a small collection of shelly fossils, namely brachiopods, such as Micromitra and Kutorgina, as well as hyoliths, such as Hyolithus. Alongside this, it also contains sparse annelid records, such as Scolecoderma. Casts of unknown foraminifera can also be found in the formation.
Lophotrochozoa
LophotrochozoaGenusSpeciesNotesImagesHyolithus Hyolithus sp. H. fistula H. malvernensis H. primaevusHyolith.Kutorgina K. cinyulata var. phillipsiiKutorginid brachiopod.Linnarssonia L. sayittalisLingulate brachiopod.Lingula (?) L. (?) squamosaLingulid brachiopod. Known fragments likely to be Kutorgina instead.Modiolopsis (?) Modiolopsis (?) sp.Mytiloid bivalve.Micromitra M. (Paterina) phillipsiPaterinid brachiopod.Obodella (?) O. (?) salteriObolellid brachiopod. Species would be reassigned to Broeggeria as B. salteri in 1902.Broeggeria B. salteriElkaniid brachiopod.
Annelida
Annelida GenusSpeciesNotesImagesScolecoderma S. antiquissimaAnnelid worm.
Incertae sedis
Incertae sedisGenusSpeciesNotesImagesColeoloides (?) Coleoloides (?) sp.Small shelly fossil of unknown affinites.
Ichnogenera
IchnogeneraGenusSpeciesNotesImagesSkolithosSkolithos sp.Burrows. Reported under its former name of Scolithus in Groom 1902.
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