Dingle Peninsula Research Articles

A polygenetic palaeosol from the Silurian (Wenlock) of southwest Ireland

A problematic palaeosol unit caps a thick basalt at the top of the Clogher Head Formation, Dunquin Group (late Wenlock, Silurian) in the Dingle Peninsula, southwest Ireland. The main part of the unit consists of an altered calc-alkaline basalt with a fine clay assemblage of chlorite, corrensite and smectite probably resulting from weathering during Wenlock times. The uppermost part of the unit consists of detrital silicates which were admixed by bioturbation and well-defined burrow-fills are present. The underlying, weathered basalt was possibly truncated before the detrital horizon was deposited, and finally the whole unit underwent a phase of surface-water gleying. A catenary relationship existed locally with the pseudo-gley developed lower in the landscape while contemporaneous basalts in topographically higher, better drained areas, largely escaped the effects of gleying; these now exhibit reddened tops. The complex history and the possiblity of the incompleteness of the profile makes accurate assessment of the soil/climate function difficult. However, the occurrence of calcrete-bearing palaeosols in the overlying Mill Cove Formation supports the view that the basalt was weathered under a sub-humid or semi-arid climate. Considering the alteration of the Dunquin Group to actinolite-prehnite grade, the preservation of the smectite is highly unusual. There is no evidence for its origin due to more recent weathering or interstratal neoformation; it is thus interpreted as a relict product of the original weathering phase.

On the trace of the Iapetus suture in Ireland and Britain

The Iapetus suture in Ireland and Britain is that line which separates Caledonian rocks of the Laurentian and Avalonian continents. The suture is cryptic: nowhere is there an exposed fault-zone containing ophiolite remnants, blue-schist melanges, or trench deposits. Instead a suture line may be traced with varying degrees of confidence through a series of faults that traverse the Iapetus suture zone, which contains two or more tectonostratigraphic terranes. Several data sets are utilized to constrain this trace. The distribution of faunal provinces caused by oceanic separation can be used most reliably to define early Ordovician terranes. Fauna1 intermingling in the mid-Ordovician reduces provinciality and the confidence of terrane identification using faunal data. The late Ordovician and particularly Silurian tectonostratigraphic histories of terranes either side of the suture suggest that amalgamation of the terranes, elimination of the Iapetus Ocean and development of the suture zone had begun by the Ashgill. Therefore the resolution of the suture trace becomes unreliable where Ordovician rocks do not crop out, because Silurian turbidite fans of Laurentian provenance may have dispersed across a significant width of Avalonian crust. Similarly, the precision of structural identification of the suture zone, by correlating the suture with a major fold-facing confrontation, may be weakened by late overthrusting. Tectonic interleaving of crustal flakes in the zone is supported by geophysical evidence which suggests that some major boundaries in the lower crust do not always coincide with their inferred projections in outcrop. Tectonic and sedimentary mixing of crustal blocks and sediments in the zone is further reflected by Nd and Pb isotopic patterns; the Rb-Sr patterns of granites record a stronger distinction between north and south of the suture. Despite these difficulties, we depict a possible suture trace in Ireland that departs significantly from the traditionally placed line by following a NE-SW-aligned trace through the Slane fault and the Navan-Tipperary lineament, and thence through a dog-leg to pass north of the Dingle Peninsula.

Analysis and tectonic interpretation of gravity data over the Variscides of southwest Ireland

The gravity data set for southwest Ireland comprising 5500 stations with a spacing of about 1–3 km has been filtered using standard wavenumber domain techniques. A band pass filtered map, emphasizing gravity anomalies originating to a maximum depth of 3–4 km, correlates well with surface geology. It shows major faults and density contrasts among six lithostratigraphical units, the most important being between the Old Red Sandstone and underlying basement. A low pass filtered map, emphasizing gravity anomalies from a maximum depth of 10 12 km shows major negative gravity anomalies at Killarney and Fermoy and positive anomalies beneath the Shannon estuary, on the Dingle peninsula and along the south coast. These data suggest that Caledonian basement was involved in Variscan deformation and any detachment lies at mid-crustal levels. Two north-south gravity profiles are modelled along Eastings 100 and 200, constrained by surface geology and published seismic refraction data. On Line 100 the source of the negative anomaly at Killarney is modelled as either a granite within basement or a deformed Devonian basin. The source of the Shannon positive anomaly is modelled as a large dense body within the crust whose southern limit coincides with the Iapetus Suture Zone. On Line 200, the Fermoy low is modelled as a laccolithic granite within basement. The positive anomaly along the south coast is a consequence of Mesozoic crustal thinning.

A deep seismic reflection transect across the Irish Caledonides

New reflection profiles recorded to 18s ( c .60km) along a 600 km north-south transect West of IREland (WIRE lines) provide a cross-section of the Irish Caledonides from Lewisian basement in the north to the Variscan fold-and-thrust belt in the south, and constrain the offshore extrapolations of major Caledonide structures. We interpret the profiles as showing the Great Glen fault and associated, NE-trending strike-slip faults as near-vertical structures which cut the whole crust and the uppermost mantle. Beneath the surface trace of the Fair Head-Clew Bay line we image a north-dipping zone which soles into horizontal layers just above the reflection Moho. The north-dipping zone separates south-dipping reflections above and to the north from north-dipping reflections below and to the south. From the Fair Head-Clew Bay line as far south as the Iapetus suture the lower crust contains north-dipping packages of reflectors possibly related to Acadian accretionary underplating. The Iapetus suture zone can be identified as a zone, more than 50 km wide, dipping north at 30° from 5 km depth offshore Dingle peninsula to sole into the Moho at c . 30 km depth west of the Shannon Estuary. In the upper crust the shallow part of the Iapetus suture zone appears to be transported to the north by late Caledonian retrocharriage or by Variscan thrusting. The Iapetus suture does not penetrate through the present-day reflection Moho, but there are scattered reflectors in the mantle not continuous with crustal reflectors, perhaps relics of a subducted slab. We recognize ‘lower-crustal’ reflectivity and the reflection Moho along almost all the WIRE profiles. Regionally the travel-time to the reflection Moho varies from 9 s ( c . 28 km?) offshore Donegal (northwest of Ireland) to 12 S ( c . 35 km?) offshore Kerry and Cork (southwest of Ireland). Apparent Moho offsets (rapid lateral changes in the travel-time to the reflection Moho) north of Donegal and north of Mayo are probably due to the Great Glen fault and associated faults. The ‘lower-crustal’ reflectivity varies considerably in thickness and prevalent dip direction along the WIRE profiles. In Donegal Bay this reflectivity is observed at depths less than 5 km ( c . 1.5s) whereas west of Kerry prominent reflectivity is only observed beneath 6s ( c . 17 km). Though the age of crustal reflectors cannot in general be determined, beneath central Ireland from Donegal to Dingle the lower-crustal reflectors mimic in dip direction the structural vergence of the exposed Dalradian and early Palaeozoic rocks, so that the lower-crustal reflectivity patterns, and probably much of the crust, must be Caledonian in age.

Fine resolution pollen analysis of vegetation history in the Lough Adoon Valley, Co. Kerry, western Ireland

The Lough Adoon Valley on the north of the Dingle Peninsula, in southwest Ireland, has been occupied by humans, perhaps continuously, since Neolothic times. Since about 5000 B.P. the valley has been essentially deforested, apart from local reinvasions of Betula, and much of the landscape has been covered by blanket bog and heath. Time series analysis of pollen and charcoal influx from two sections of peat sampled at contiguous 1 cm intervals was carried out to explore the vegetation shifts associated with Betula decline and charcoal dominated phases. Cereal cropping and fire were important vegetational controls resulting in an interplay between heath, wetland, grassland and woodland but forest decline was not a result of fire. The number of pollen taxa interrelationships differed between the phases with a greater number of interrelationships in the Betula decline phase than when fire was more prominent in the environment.

Lithostratigraphy and structure of the old red sandstone of the Northern Dingle Peninsula, Co. Kerry, Southwest Ireland

AbstractThe lower part of the Old Red Sandstone in the Dingle Penisula has been previously assigned to one lithostratigraphic group (Dingle Group) despite marked variations in sedimentary facies. However the apparently oldest non‐marine sequence in the northwest of the peninsula has sedimentary and lithological attributes that contrast strongly with those of the late Silurian‐early Devonian Dingle Group to the south. This northern sequence, here renamed the Smerwick Group, evolved independently of the Dingle Group in a separate basin of deposition. Field relationships between the two groups in the north of the peninsula are interpreted as indicating that the Smerwick Group overlies, with angular unconformity, a normal Dingle Group succession. Similarly, it is argued that the Smerwick Group overlies, with angular unconformity, the Dingle Group in the northwest of the peninsula, but there the Dingle Group is attenuated, represented only by a conglomerate unit some 10 m thick. In the absence of biostratigraphic evidence the age of the Smerwick Group is poorly constrained. Nevertheless, we propose a tectonic model that suggests that the Smerwick Group evolved within a small extensional half‐graben on the northern margin of the Munster Basin. This model accounts for the stratigraphic and structural relationships observed, and implies that the Smerwick Group is of Late Devonian age.

The fossiliferous Silurian rocks of the Dunquin inlier, Dingle Peninsula, County Kerry, Ireland

ABSTRACTThe history of investigation of the Silurian rocks of the Dunquin inlier, Dingle Peninsula, County Kerry, Ireland is briefly reviewed. The Dunquin Group of upper Wenlock (Homerian) to middle Ludlow (Ludfordian) sedimentary and volcanic rocks is divided into five formations: the Ferriters Cove, Clogher Head, Mill Cove, Drom Point and Croaghmarhin Formations, the last of which reaches the Ludlow and passes transitionally into the succeeding continental Dingle Group, probably largely Přídolí in age. The Dunquin group is of varied shallow marine sediments with a continental episode probably represented in the Mill Cove Formation. The biostratigraphy of the other four formations is considered in relation to a full faunal list. Details of representative sections and exposures are provided. There is brief comment on the palaeogeographical setting of the inlier.

The Best of Two Worlds, the Worst of Two Worlds: Reflections on Culture and Field Work among the Rural Irish and Pueblo Indians

Despite its title this article does not pretend to be or to offer a study in comparative ethnography, since my expertise in the cultures to be discussed is limited and uneven. I know somewhat more about the rural Irish of the Dingle Peninsula, among whom I lived during 1974–75, than I do about the Pueblo Indians of New Mexico, among whom I spent the greater part of the summer in 1979 and again in 1985. Nor do these remarks have any pretense to social history, although it is to these peoples' collective responses to aspects of their histories that the article is addressed. Rather, it should be taken as a critical reflection on the vulnerabilities of the human spirit and on the vulnerabilities of a science that tries to pierce the meanings of that spirit. It is a tale of two cultures, and of the ethnographer as a teller of tales, and of the pitfalls of cultural interpretation.

Pre‐Caledonian basement in Ireland and its cover relationships

AbstractPre‐Caledonian basement is exposed in three areas within the Irish orthotectonic Caledonides: 1. In northwest County Mayo the Erris Complex comprises the Annagh Division, which is largely Grenvillian but includes older gneisses, and the Inishkea Division, which is probably equivalent to the older Moines of Scotland. 2. In the northeast Ox Mountains, Rosses Point and Lough Derg inliers there is a granulite fades, dominantly metasedimentary basement which is probably late Grenville in age. 3. Laxfordian and probably older gneisses are seen in the Inishtrahull Platform northeast of Malin Head, County Donegal.In addition, some gneisses within the belt of ‘Connemara migmatites’ in south Connemara may be fragments of allochthonous basement and some high grade metamorphic rocks in the Tyrone Central inlier have been referred to as pre‐Caledonian basement, but there is at present no conclusive support for these suggestions. The Ox Mountains succession seen in the Clew Bay region and the southwest and central Ox Mountains is probably not pre‐Caledonian basement.Basement in the paratectonic Caledonides is confined to the Cadomian and possibly pre‐Cadomian Rosslare Complex (older than 625 Ma) and the nearby late Precambrian (to early Cambrian ?) Cuilenstown Formation in southeast County Wexford. In addition, an unseen block of basement defined by magnetics immediately to the north of the Dingle peninsula of County Kerry is probably of Rosslare Complex affinity. Granulite facies xenoiiths recovered from volcanic rocks of Carboniferous age about 70 km to the west of Dublin, indicate the character of basement there, though its age is not proven.All contacts between basement and Lower Palaeozoic Caledonian cover in the orthotectonic Caledonides are synmetamorphic slide zones and faults and in the paratectonic Caledonides the contacts are either faults, which are often rooted in older mylonites, or are unexposed and presumed to be major structural breaks.

Saints, Scholars, and Schizophrenics: Mental Illness in Rural Ireland.

TWENTIETH ANNIVERSARY EDITION, UPDATED AND EXPANDED When Saints, Scholars, and Schizophrenics was published twenty years ago, it became an instant classic--a beautifully written study tracing the social disintegration of Ballybran, a small village on the Dingle Peninsula in Ireland. In this richly detailed and sympathetic book, Nancy Scheper-Hughes explores the symptoms of the community's decline: emigration, malaise, unwanted celibacy, damaging patterns of childrearing, fear of intimacy, suicide, and schizophrenia. Following a recent return to Ballybran, Scheper-Hughes reflects in a new preface and epilogue on the well-being of the community and on her attempts to reconcile her responsibility to honest ethnography with respect for the people who shared their homes and their secrets with her.

REVIEWS OF BOOKS

ATLAS OF IRELAND. Prepared under the direction of the National Committee for Geography. Dublin: Royal Irish Academy, 1979. vii + 104 pp. £45.00. Reviewed by: J. H. Johnson NORTHERN IRELAND: A CENSUS ATLAS, by P. A. Compton. Dublin: Gill and Macmillan, 1978. 169 pp. £15.00. Reviewed by: B. W. Langlands DISPLACEMENT AND DEVELOPMENT: CLASS, KINSHIP AND SOCIAL CHANGE IN IRISH RURAL COMMUNITIES, by Damian F. Hannan. Dublin: Economic and Social Research Institute Paper No. 96, 1979, 231 pp. £5.00. Reviewed by: Mary E. Cawley IRISH RESOURCES AND LAND USE, edited by D. A. Gillmor. Dublin: Institute of Public Administration, 1979. 295 pp. £11.99. Reviewed by: F. Walsh IRELAND'S WETLANDS AND THEIR BIRDS, by Clive Hutchinson. Dublin: Irish Wildbird Conservancy, 1979. 201 pp. £4.95. Reviewed by: Stu Daultrey IRISH FORESTRY POLICY, National Economic and Social Council Report No. 46 (by Frank J. Convery). Dublin: Stationery Office, [1979]. 225 pp. £2.25. Reviewed by: M. B. Thorp URBANISATION AND REGIONAL DEVELOPMENT IN IRELAND, National Economic and Social Council Report No. 45 (by P. N. O'Farrell). Dublin: Stationery Office, [1979]. 128 pp. £1.65. Reviewed by: F. W. Boal AN ANALYSIS OF NEW INDUSTRY LOCATION: THE IRISH CASE, by P. N. O'Farrell. Oxford: Pergamon Press, Progress in Planning, 9 (3), 1978. 129–229. £4.00. Reviewed by: J. A. Walsh I.D.A. INDUSTRIAL PLAN 1978–82. Dublin: Industrial Development Authority, 1979- 77 PP- £2.97. Reviewed by: M. J. Bannon THE IRISH HOUSING SYSTEM: A CRITICAL OVERVIEW, by T. J. Baker and L. M. O'Brien. Dublin: Economic and Social Research Institute Broadsheet No. 17, 1979, 272 pp. £4.50. Reviewed by: Andrew MacLaran THE GEOGRAPHY OF IRELAND, by Joseph P. Haughton and Desmond A. Gillmor. Dublin: Department of Foreign Affairs, 1979. 59 pp. £2.50; FACTS ABOUT IRELAND. Dublin: Department of Foreign Affairs, 1979. 258 pp. £3.30. Reviewed by: S. Waterman THE ISLANDS OF IRELAND, by Kenneth McNally. London: Batsford, 1978. 168 pp. £7.95. Reviewed by: F. H. A. Aalen THE TORY ISLANDERS: A PEOPLE OF THE CELTIC FRINGE, by Robin Fox. Cambridge: Cambridge University Press, 1978. 210 pp. £3.95. Reviewed by: F. H. A. Aalen THE LANDSCAPE OF SLIEVE BLOOM, A STUDY OF ITS NATURAL AND HUMAN HERITAGE, by John Feehan. Dublin: BlackwatEr Press, 1979. xix+284pp. £10.00. Reviewed by: Colin A. Lewis COBH: ARCHITECTURAL HERITAGE, by William Garner. Dublin: An Foras Forbartha, 1979. 86 pp. £1.50. Reviewed by: Kevin Hourihan GEOLOGICAL SURVEY OF IRELAND GUIDE SERIES: I. GEOLOGICAL GUIDE TO THE DINGLE PENINSULA, by Ralph R. Home. First edition 1976, revisions to 1979. £1.00; 2. FIELD GUIDE TO THE CALEDONIAN AND PRECALEDONIAN ROCKS OF SOUTH-EAST IRELAND, by P. M. Bruck, P. R. R. Gardiner, M. D. Max and C. J. Stillman. 1978. £3.00; 3. A TRAVERSE IN THE NORTH-WEST IRISH CALEDONIDES, by T. B. Anderson, D. H. W. Hutton, W. E. A. Phillips and J. C. Roberts. 1978. £1.50; GEOLOGICAL SURVEY OF IRELAND INFORMATION CIRCULAR 79/1: WATER WELLS. 1979. Reviewed by: R. J. N. Devoy THE QUEEN'S UNIVERSITY OF BELFAST DEPARTMENT OF GEOGRAPHY JUBILEE 1928–1978: GEOGRAPHY AT QUEEN'S, AN HISTORICAL SURVEY, by John A. Campbell. Queen's University Department of Geography, Departmental Research Paper No. 2, 1978. 55 pp. Reviewed by: Gordon L. Herries Davies

The Association of Alluvial Fan, Aeolian and Fluviatile Facies in the Caherbla Group (devonian), Dingle Peninsula, Ireland

ABSTRACT The Caherbla Group (Devonian) in the Dingle Peninsula of southwest Ireland is a consanguineous association of alluvial fan, aeolian and fluviatile lithofacies. These sediments accumulated in an elongate trough adjacent to a source ridge composed largely of high-grade metamorphic rocks. Two laterally equivalent, inter-fingering formations are recognized. The Inch Conglomerate Formation is an alluvial fan deposit containing blocks of schist and gneiss up to 75 70 60 cm in size in a sparse red sandy matrix. It fines north-westwards away from the proposed source area. The Kilmurry Formation is composed very largely of aeolian sandstones with large-scale dune cross-stratification. Thes aeolian sandstones are interbedded with and largely laterally equivalent to the fan breccio-conglomerates of the Inch Conglomerate Formation. The dune fields developed between the fans and on their lower slopes. Interbedded with these dune units are lenticular sequences of fluviatile sandstones and mudstones representing the channel fill of impermanent rivers impounded by dune sands and engulfed by them during dry periods.

Some points of interest concerning the Silurian inliers of southwest central Ireland in their geosynclinal context: a statement

In his discussion of geosynclinal development in the Silurian of the British Isles, Ziegler (1970) distinguishes land masses, shelf deposits, turbidite deposits and graptolitic shales. He further distinguishes between blocks such as the Midland Block and Eocaledonia (where passage from shelf to turbidite facies is sharp and associated with major fractures) and tectonic lands such as Cockburnland or the Irish Sea Land Mass (where the shelf record is only in the form of slumped shelly deposits). Ziegler extrapolates his palaeogeographic maps across Ireland—a slimly documented area. He tentatively places the shelly succession of the Dingle Peninsula as part of the southern margin of Eocaledonia, and asserts that the turbidites and associated deposits of the Central Inliers seem to be related to the northern (Eocaledonian) margin of the trough. A contrary view has been suggested by Holland (1969 p. 208) who thinks that the Irish Sea Land Mass might have contributed sediments from the east. Ziegler's palaeogeographic maps (op. cir. Figs. 3–6) show the trough as asymmetric, with turbidites mainly confined to the north-western side and graptolitic shales to the south-east. The evidence for this palaeogeographic interpretation in Ireland is slender and his conclusions are presumably based on his interpretation of the geology of the Central Inliers. As will be seen in the following account there are some points concerning these inliers which are worthy of mention although their explanation is by no means clear. The inliers are thought to fall into two groups and the argument for this is

Aeolian cross-stratification in the Devonian of the Dingle Peninsula, County Kerry, Ireland

SummaryCross-stratified units, of the order of 1 to 12 m thick, are described from the Devonian Slieve Mish Group in the Dingle Peninsula of south-west Ireland. They are composed entirely of purplish-red or yellowish-grey and violet, medium- to fine-grained sandstone. An aeolian origin for this cross-stratification is indicated by the large size and morphology of the fore-sets, the excellent sorting of the sandstones and the associated evidence of aridity in a continental environment within a restricted basin.

The glaciation of the Dingle Peninsula

The glaciation of the Dingle Peninsula

The glaciation of the dingle peninsula

The glaciation of the dingle peninsula

Points from Foregoing Letters

In a note on the early use of current-bedding to determine orientation of strata in the Dingle Peninsula, Eire, A. Lamont raises the question of the parts played by Patrick Ganly, John Kelly, and possibly G. V. Du Noyer in the application of this technique.

First Use of Current-Bedding to Determine Orientation of Strata

DR. ROBERT M. SHACKLETON1 has recently completed a revision of the structures of the Silurian and Devonian rocks of the Dingle Peninsula and Blasket Islands in south-west Eire. In this he has used the positions of truncated tops and asymptotic bases of current-deposited laminae in order to determine the correct order of succession, and has been able to demonstrate the probable equivalence of Anascaul Beds with Ferriter's Cove and Croaghmartin Beds (Silurian) and of Smerwick Beds with Dingle Beds (Downtonian). Axes of folding that trend from east-north-east to west-south-west have been plotted, and inverted beds are conclusively recognized on the north and south margins of the Peninsula and at Clogher Head. The final proof that the axis of an overfolded syncline runs through Ventry Harbour, Fahan Point, and between the Great Blasket and the two smaller islands of Inishnabro and Inishvickillane, vindicates the work of G. V. Du Noyer prior to 1859 in first tracing the inversion south of this important line and describing it despite opposition by J. Beete Jukes2, director of the Irish Geological Survey.