Tully Hill

Site of Special Scientific Interest · 54.9728, -6.5578

Also within

Londonderry County

Geology & landscape

Geological Feature: Esker · Geological Period: Quaternary

Landscape processes: Glacial

Description

Tully Hill Pleistocene Tully Hill is of importance in understanding the recent glacial history of Northern Ireland. The landscape of the Kilrea area has been defined by events that occurred towards the end of the last Ice Age, between 17,000 and 13,000 years ago, a period of gradual climatic warming. The Tully Hill area comprises a major flat-topped delta and associated ridges formed during a period of rapid ice retreat. It is an outstanding example of this deglacial landform assemblage. The Tully Hill complex, when assessed in the context of the wider area, provides a range of sedimentary and geomorphological evidence which explains the nature of deglaciation in the mid Bann valley. The deposits demonstrate a general north to south pattern of ice-mass retreat during deglaciation and also that the rate of ice-front retreat was not constant, but rather varied, from relatively rapid retreat to periods of temporary halting. As ice retreated southwards, a lake formed with water and sediment coming from the adjoining glacier. The structure of Tully Hill indicates that it was formed from sediments deposited by a high velocity stream flowing beneath the ice mass into the lake, while its southern steep side suggests contact with an ice mass. The height of the hill compares well with that of another delta to the south, on which Kilrea is built. These deltas record temporary halts in the retreat of the glacier front, when sediments built up almost to the level of the water body surface. That both deltas show similar elevations indicates a static lake level of around 40m above sea-level in the mid Bann valley. The ridge or esker deposits adjoining the southern slopes of the hill are thought to represent the courses of stream that flowed below the ice, feeding sediment into the lake. https://www.daera-ni.gov.uk/publications/tully-hill-assi

Plant communities

A9 — Fast flowing river and stream, Marginal and inundation, Pond ditch and canal, Sluggish river and stream

Potamogeton natans community

Schoenoplectus 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

Isolepis 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

Berula 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

Fontinalis 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