Conservation areas River Avon, Bristol

new bridge, bath close newton st loe sssi, painted in 1806

the avon gorge has been designated site of special scientific interest because supports rare fauna , flora, including species unique gorge. there total of 24 rare plant species , 2 unique trees: bristol , wilmotts s whitebeams. other notable plants include bristol rock-cress, bristol onion, spiked speedwell, autumn squill , honewort. other areas along river have designation include bickley wood, cleeve wood, hanham large population of bath asparagus (ornithogalum pyrenaicum). stidham farm near keynsham contains @ least @ least 2 metres (7 ft) of pleistocene terrace-gravels, consisting of limestone clasts mainly, millstone grit, pennant sandstone, flint , chert clasts. site of considerable importance studies relating possible glaciation of area, , of terrace stratigraphy, particularly 1 of 2 accessible terrace deposits in part of avon valley. newton st loe sssi listed geological reasons represents remaining known exposure of fossiliferous pleistocene gravels along river avon. in conjunction other sites within wider area, have aided development of scientific understanding of history of glaciation within south west england.

at horseshoe bend, shirehampton wooded cliff , narrow salt marsh supported rocks of devonian sandstone , carboniferous limestone, overlain triassic dolomitic conglomerate. site s principal interest , reason designation sssi presence of population of true service-tree (sorbus domestica) growing on cliffs. tree nationally rare in britain, , site hosts largest known population in england. other notable species of sorbus here whitebeams sorbus eminens , sorbus anglica, both of nationally rare in britain. nationally scarce large-leaved lime (tilia platyphyllos) occurs, , herbs include field garlic (allium oleraceum) , pale st. john s-wort (hypericum montanum). saltmarsh vegetation, lies @ base of cliff, predominantly made of sea aster (aster tripolium) , english scurvygrass (cochlearia anglica). there 2 nationally scarce vascular plant species here well – slender hare s-ear (bupleurum tenuissimum) , long-stalked orache (atriplex longipes).

the tidal reaches of river avon provide habitat waterbirds, 64 species having been recorded 2004, including 21 species of shorebird, , 13 species of gull.