| Previous Site | Next Site |
Earth Science Conservation Review
| Woodgrange | Down |
| Site number: | 6 | File Number: | J44 |
| ESCC: | IS | ||
| Locality Type: | Inland exposure | Status: | ASSI |
| Grid Reference: | J440445 Centroid | ||
| Google maps: | 54.32935,-5.78644 | ||
| County: | Down | Council area: | Newry, Mourne & Down District Council |
| Period: | Quaternary | ||
| Stages: | Late Midlandian, Pleistocene | ||
| Site Description | |
|---|---|
| Highlights: | |
The site at Woodgrange has been selected as the type site for late-glacial climatic oscillation following deglaciation in Ireland. Although many of the late-glacial sites in Ireland record a common sequence of events, Woodgrange records the very first plant colonisation possibly around 13,000 years ago (Watts, 1985). The succeeding grass phase (11,800 - 10,900) is best represented at Woodgrange and was formerly termed the Allerod interstadial by Jessen (1939). Postglacial estuarine clays were deposited after about 7000 yrs B.P. | |
| Introduction: | |
The Woodgrange site is a drained estuarine basin which is about 0.8km north of Magheralagan lake near the edge of the Quoile watershed. The small basin is almost totally surrounded by drumlin ridges which provide run off towards the centre of the basin and a local relief of around 30m. The bed of the basin outlet is at about 3.5m O.D. and is marked by a small stream which drains eastwards towards the Swan Island flats. Present surface vegetation is essentially fen and marsh. The U-shaped interdrumlin tract of the basin is dominated by two shallow depressions. Details and cores taken by Gurdip Singh were published in 1970 and document the palaeoecological evidence for late-glacial climatic change. Results from this study highlight the problems surrounding late-glacial vegetational development and its likely relationships to the tripartite lithostratigraphy found in many late-glacial sites (Singh, 1970). Later Singh and Smith (1973) published detailed work on the later post-glacial vegetational history of the Lecale area in association with relative land and sea level changes. They recognised a considerable diversity in the extent of human interference on the vegetation patterns. | |
| Description: | |
THE LATE GLACIAL: The stratigraphy of the Woodgrange basin was constructed from a series of borings (Singh, 1970). Detailed stratigraphy was built up from field observations and macro-analysis of individual samples taken for pollen analysis from point 4 in section BB1. The lithostratigraphy is as follows: cm description 591-640 light-grey clay with very few plant remains. Moss shoots common. 600cm moss shoots very common. 620cm a few Juncus seeds. 640-650 dark-grey slightly sandy clay-mud. 650-661 light-grey clay. 650cm some Characeae nucules. 661-675 dark-grey clay-mud; with thin lenses of lighter coloured clay. 675-732 dark-grey clay-mud; lighter coloured lenses less frequent. Occasional nucules of Characeae present. 732-774 light-grey marl. Characeae nucules common. Moss fragments fewer in number. 774-778 dark-grey clay-mud. 778-810 pink clay. 810- gravel. The new zonation scheme was adopted for a variety of reasons. One important consideration was the non-synchroneity of lithological and vegetational changes. Another involves the relative proximity of glacial refugia which introduces an unknown element of metachroneity (Smith, 1965). The lower inorganic deposit, as has been seen at the other two sites, contains abundant pre-Tertiary spores which are found together with pollen of Corylus, Alnus, Pinus and Quercus. The lowermost sample also contained a few grains of Engelhardtia. From the fact that the tree pollen curves decline at the same time as the fall of the 'derived spores' curve, it can be reasonably assumed that most of this pollen is derived from earlier deposits. In an attempt to remove this factor from the pollen diagram, 'tree and shrub' and 'land herb' pollen ratios were recalculated after excluding the pollen of thermophilous trees from the pollen sum. The resulting ratio curve shows 'land herb' pollen to be overwhelmingly dominant over 'tree and shrub' pollen. In zone I, 'land herb' pollen is mainly represented by Gramineae, Cyperaceae, Rumex acetosa-type and Rosaceae. Among trees and shrubs only Salix, represented largely by S.herbacea-type, shows a consistent increase in frequency. The Betula curve shows low values. Caryophyllaceae, Umbelliferae, Chenopodiaceae and ferns are well represented. Pediastrum colonies attain their maximum frequency in this zone. Zone I/II Transition begins at 765cm, zone II at 735cm, and zone III at 650cm. The general run of most pollen curves in zones II and III is similar to the other sites though pollen of Helianthemum, Thalictrum and Hippopha‰ is particularly well represented in zone II. One of the most interesting features of the Woodgrange diagram is the occurrence of small amounts of pollen of Cladium mariscus in zone II. Two grains of Cladium also occur in zone III and one in zone I/II. Zone III/IV Transition is quite distinct in the Woodgrange diagram. It begins where the Filipendula pollen curve rises (at 605cm) accompanied by a rise in the Empetraceae curve. The Betula curve which rose slightly at the 610cm level maintains low values. Along with the appearance of the Filipengula pollen curve, pollen of Urtica, another relatively thermophilous plant and Cladium mariscus makes its appearance. The zone ends at 590cm where the curve for Betula shows a sudden rise and the 'land herb' pollen values decline abruptly. The Juniperus pollen curve, which rises in this transitional zone, soon falls away again. THE POST GLACIAL Levelled borings and excavations show the stratigraphy of the postglacial sequence in the northwestern part of the Woodgrange basin. Section BB1 illustrates the detailed stratigraphical record. It is important to note that the presence of Hystrichosphaerideae indicate that parts of the basin came under occasional marine influence prior to the deposition of estuarine clay. The basal part of the latter is dated to 6,550 ± 300 B.P. (LJ-903; Hulbs, Bien and Suess, 1965). Other dates from the organic layer below the marine sand are 7,220 ± 175 B.P. and 6,565 ± 105 B.P. (UB-431; Dresser, Smith and Pearson, 1973). The maximum of the sea level rise is represented by a sand layer at 6.1m O.D. A 14C date of 3,380 ± 180 B.P. (LJ-908) from the lowermost part of the brackish water clay (without shells), overlying the shell bed, approximately tallies with the 14C assay of 3,125 ± 150 B.P. (I-1199) obtained from the upper organic deposit in contact with the marine sand in the raised beach deposits. Further radiocarbon dating of organic deposits below the Woodgrange raised beach confirms it was deposited before 3,000 B.P. (Dresser, Smith and Pearson, 1973). Actual dates on the salt-water to freshwater conditions in the basin are obscured by several factors among which is the building of the barrage across R. Quoile in 1745 (Knox, 1875). | |
| Importance: | |
The late-glacial sequence at Woodgrange illustrates the first colonisations by plants after the last glaciation and a series of pollen spectra which document late-glacial climatic oscillations. It also demonstrates that considerable local and regional variation in the late-glacial vegetative communities existed when compared to other known sites. On this basis the late glacial sequence at Woodgrange is of national importance though important vegetational characteristics make the site of international significance. The presence of post-glacial estuarine deposits infilling the basin is mainly of local interest. However, it should be stressed that this is one of the few sites where elements of the post- glacial transgression have been subjected to 14C dating. Although in many respects the results are not conclusive the site does facilitate comparisons between inland and more open sites on the coast. In this respect the post-glacial estuarine fill is of national significance. One of the pollen diagrams from this site records a 'landnam phase' which has local importance. | |
| Interpretation: | |
THE LATE GLACIAL Zone 1: Pollen curves consist largely of herbaceous pollen indicating open conditions with 'land herb' pollen exceeding 80%. The pink clays which constitute the earliest zone 1 deposits contain marine fossils as well as fresh water aquatic plants and have been variously interpreted as marine (Stephens, 1963) or resedimented (Singh, 1970). However given the low threshold of the basin and the close association between the red mud drape and notches up to 16-17m on drumlins on the open coast, it is likely that the late-glacial sea flooded this area. Zone I-II Transition: Singh (1970) considers that the great rise in Juniperus values during the I/II transition and declines in the curves of herbaceous elements is partially statistical. The presence of Typha latifolia may suggest climatic improvement and the substantial amounts of Empetraceae pollen are indicative of oceanic conditions (cf. Jessen, 1949). Betula pollen curves show little change from values in Zone I. Zone II: Singh (1970) considers that an actual rise in birch pollen and presence of fruits of Betula cf. pubescens represents tree birch stands in the area. Overall low pollen frequencies of Betula may have been masked by the high frequencies of Gramineae pollen. It is suggested that the tree cover, represented by the Betula pollen curve, was much more sparse than that at other Irish sites of this age. However, it may have been close to its climatic limit (Watts, 1985). An important feature of Zone II is a sudden fall in the Juniperus pollen values at the beginning of this zone. Singh (1970) suggests this local trend may be a result of a decrease in oceanicity and the presence of more severe winters. 'Land herb' pollen values remain above 75% with a grass-sedge vegetation and scattered trees of Betula pubescens together with light-demanding herbaceous plants. In the second half of Zone II Betula and Gramineae pollen curves decline and the curves of Artemisia, Rumex, Caryophyllaceae and Rosaceae begin to increase. Zone III: In this zone the grass curve declines and the Juniperus curve continues to show low values. A major change of vegetation then followed to dwarf willow, Artemisia, Caryophyllaceae and diverse herbs. The tundra-like vegetation contained 'chianophilous' elements such as Salix herbaceae and Rumex acetosa, numerous open habitat species and many light-demanding herbs. Zone III/IV Transition: This is represented in the 'inorganic' part of the sediment and shows Juniperus rising to its maximum and a rise in the Corylus curve which suggests that Corylus trees cannot have been far removed from the site. The pollen of relatively thermaphilous species (Cladium, Urtica and Filipendula) are represented. Cladium mariscus requires high summer temperatures of 14° to 16°C in the warmest months to flourish. THE POST GLACIAL Above the late glacial deposits the basin is largely filled with estuarine clays which are intercalated with freshwater organic deposits. Pollen evidence suggests occasional marine influence before estuarine clay deposition around 7,650 ± 460 B.P. The sand layer is interpreted as the highest limit of the spring tides at the maximum of relative sea level rise and is thought to have been deposited around 3,000 B.P. Deposition of brackish water clays followed until at least 2,710 ± 150 B.P. though the actual date of transition from salt- to freshwater is obscured. Estimates of sea level change on the open coast cannot be readily compared with those from sites such as Woodgrange that are sited inland. | |
| Conclusions: | |
The interdrumlin basin at Woodgrange contains three main stratigraphic elements. Drumlin sediments are draped by a pinkish clay which seems to represent resedimented marine clay associated with the later glacial transgression. Overlying terrestrial sediments are of late-glacial age and contain rich floristic elements associated with late-glacial climatic oscillations and local edaphic diversity. The main basinal fill is associated with quiet water, estuarine conditions which occurred around 7,500 yrs B.P. during the post-glacial marine transgression in eastern County Down. | |
| Notes: | |
All of the stratigraphy is buried in the interdrumlin hollow though shallow excavations on the basinal margins can reveal the feather edge of the post-glacial transgression. The boundary of the site is therefore placed along the local watershed which would maintain the overall integrity of the site. | |
| Keywords | |
|---|---|
| Fossil Groups: | Plant |
| Relations: | Interstadial, Late-glacial deposit |
| Geomorph: | drumlin, estuarine clays, pollen analysis |
| Access | |
|---|---|
| Approach: | 5km W of Downpatrick. |
| Management: | |
This site requires little active management because all of the stratigraphic units are buried and unlikely to be disturbed. However the following notifiable operations should be observed: 1: Modification of the land surface, subsurface, water levels or water courses. The site should not be drained as it would alter the present vegetation. 2: Field/field boundary drainage. 3: Alternation of water levels, water table or utilisation of water. 4: Use of any vehicles. 5: Any extraction. 6: Afforestation/tree planting. 7: Any cultivation/application of slurry, lime, fertiliser. 8: Burning of waste. 9: Dumping, spreading or discharge of any materials. | |
| Uses | |
| Uses: | The basin itself is not used intensively because of the presence of marsh and a high water table. It is used for rough grazing in summer. Surrounding drumlin slopes are grazed and used for silage. |
| References (10) | |||
|---|---|---|---|
| Dresser, P.Q., Smith, A.G. & Pearson, G.W., 1973. Radiocarbon dating of the raised beach at Woodgrange, Co. Down. Proceedings of the Royal Irish Academy, vol. 73B, pp.58-290. | |||
| Hubbs, C.L., Bein, G.S. & Seuss, H.E., 1965. Radiocarbon, vol. 7, pp.66. | |||
| Jessen, K., 1949. Studies in Late Quaternary deposits and floral history of Ireland. Proceedings of the Royal Irish Academy, vol. 52B, pp.85-290. | |||
| Knox, A., 1875. A History of the County of Down., Dublin. | |||
| Singh, G., 1970. Late glacial vegetational history of Lecale, Co. Down. Proceedings of the Royal Irish Academy, vol. 69B, pp.189-216. | |||
| Singh, G. & Smith, A.G., 1966. The post-glacial marine transgression in N. Ireland. Conclusions from estuarine and raised beach deposits. A contrast. Palaeobotanist, vol. 15, pp.230-234. | |||
| Singh, G. & Smith, A.G., 1973. Post-glacial vegetational history and relative land and sea-level changes in Lecale, Co. Down. Proceedings of the Royal Irish Academy, vol. 73B, pp.1-51. | |||
| Smith, A.G., 1965. New Phytologist, vol. 57, pp.363-386. | |||
| Stephens, N., 1963. Late glacial sea levels in north-east Ireland. Irish Geography, vol. 4, pp.345-359. | |||
| Watts, W.A., 1985. Quaternary vegatation cycles. In The Quaternary History of Ireland, pp.155-185 Academic Press, London. | |||
| Map(s): | See the 1:50,000 O.S. Sheet 21 (Strangford Lough). | ||
| Record type: | Environment Serv. GIS, ESCR report, J. Preston l | ||
| Entered by: | Crowther, P.R. | ||
| Enlander, I., Dempster, M. & Doughty, P., 2026. Woodgrange, County Down, site details. [In] Earth Science Conservation Review. https://www.habitas.org.uk/escr/site.php?item=6. Accessed on 2026-11-07. |
| Previous Site | Next Site |