Bullhill Brook
Also within
Condition (Natural England)
| Unit | Feature | Condition | Area (ha) | Assessed |
|---|---|---|---|---|
| SJ555015 | — | Favourable | 0.32 | 2015-03-21 |
Habitats
Geology & landscape
Geological Period: Ordovician · Rock Type: Sandstone, Shale
Description
Description The site consists of a stream section approximately 200 metres long in Bullhill Brook, about eight kilometres north west of Much Wenlock. The exposures in Bullhill Brook lie within the Arenaceous Beds, forming the uppermost division of the Shineton Shale Formation of the Tremadoc Series. The Arenaceous Beds belong to the uppermost part of the Shumardia salopensis Biozone and consist of a series of laminated or micaceous shales interbedded with seams of grit or sandstone. The latter show flute and prod marks on their basal surfaces, indicating that they originated as turbidites. Bullhill Brook is the only site where a fossil fauna has been recovered from the Arenaceous Beds. The Arenaceous Beds contains a rich fauna of exceptionally well preserved trilobites representing the families Diplagnostidae, Metagnostidae, Asaphidae, Cheiruridae, Olenidae, Orometopidae, Remopleurididae and Shumardidae. Several of the trilobite species are new and the types originate from this site. The fauna also contains five genera of calcichordates including a new genus, Prochauvelicystis and Anatifopsis, a new genus of eocrinoid. Inarticulate brachiopods also occur. The trilobite genera consist of widespread taxa and as such are typical of an outer shelf fauna. However the absence of any planktonic fauna in the form of graptolites indicates these beds may have been deposited in a basin largely cut off from oceanic circulation. The relative abundance of olenid trilobites at some levels indicates periodic low oxygen concentrations in the water. The calcichordates and shumardiid trilobites were both adapted for semi infaunal feeding, indicating that the muds were rich in organic material. This site is important not only for its fauna, but because it represents the youngest rocks of Tremadoc Series age east of the Church Stretton Fault complex and indicates that shelf margin conditions penetrated onto the Midland Craton at this time. This is an important site for stratigraphical and palaeogeographical studies of the Lower Ordovician in Britain.
Plant communities
A9 — Fast flowing river and stream, Marginal and inundation, Pond ditch and canal, Sluggish river and stream
Potamogeton natans community
Show 20 indicator speciesSchoenoplectus lacustris, Juncus bulbosus, Sparganium angustifolium, Sparganium erectum, Sparganium minimum, Alisma plantago-aquatica, Lobelia dortmanna, Equisetum fluviatile, Myriophyllum alterniflorum, Elodea canadensis, Lemna minor, Lemna trisulca, Nymphaea alba, Callitriche platycarpa, Callitriche stagnalis, Littorella uniflora, Potamogeton natans, Ranunculus trichophyllus, Glyceria fluitans, Chara subspinosa
A14 — Fast flowing river and stream
Myriophyllum alterniflorum community
Show 15 indicator speciesIsolepis fluitans, Juncus bulbosus, Fontinalis antipyretica, Lobelia dortmanna, Equisetum fluviatile, Myriophyllum alterniflorum, Lemna minor, Callitriche stagnalis, Littorella uniflora, Potamogeton filiformis, Potamogeton gramineus, Potamogeton natans, Ranunculus peltatus, Chara spp., Nitella hyalina
A17 — Chalk river and stream, Fast flowing river and stream
Ranunculus penicillatus ssp. pseudofluitans community
Show 11 indicator speciesBerula erecta, Nasturtium officinale, Elodea canadensis, Lemna minor, Callitriche stagnalis, Veronica beccabunga, Polygonum amphibium, Polygonum hydropiper, Potamogeton crispus, Potamogeton pectinatus, Ranunculus penicillatus ssp. pseudofluitans
A18 — Fast flowing river and stream
Ranunculus fluitans community
Show 12 indicator speciesFontinalis antipyretica, Fontinalis squamosa var. curnowii, Myriophyllum alterniflorum, Myriophyllum spicatum, Elodea canadensis, Mentha aquatica, Lemna gibba, Lemna minor, Potamogeton perfoliatus, Ranunculus fluitans, Glyceria fluitans, Phalaris arundinacea