IQUA Newsletter 34
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I QUA Newsletter April 20QSj IQUA Cumann Re Cheathartha na h-Eireann Irish Quaternary Association http://www.tcd.ie/Geography/IQUA/lndex.htm April 2005 NS 34 ISSN 0790-4096 Editor: Catherine Dalton 1. Introduction A smaller audience was in attendance for the Spring Meeting and AGM 2005. Fraser Mitchell questioned how we could make the Spring Dear All, meeting more popular, especially among young researchers and postgraduates. It was I became a member of the RIA Geography suggested that the meeting next year be led by committee in November 2004 and now have postgraduates. additionally been co-opted as a member of the RIA Geosciences committee. I hope to represent the The treasurer’s report reflected the successful interests of IQUA on both committees. year. Lapsed members were encouraged to re subscribe and the corporate members were Catherine Dalton encouraged to pay two years in advance. The guide books sales are also well up on previous years. There are presently 85 paid members. 2. IQUA Fieldmeeting 2005 A suggestion was made to re-instate a prize for There will be no annual fieldmeeting this year, due the best postgraduate talk at the Spring meeting. to the QRA / IQUA fieldtrip April 5-9,h 2005. This will be discussed at the next committee meeting. Proposals for the 2005 Autumn Symposium 3. IQUA Spring Meeting & AGM included ‘Reconstructing Changing Climates’. 2005 Susan Hegarty (UCD) and Freea Itzstein-Davey (TCD) have offered to organise the event. A The IQUA AGM took place on Saturday, March provisional date of 25th of November has been 12th, in the Museum building, TCD. In general, it suggested. was thought that IQUA had a successful year. Special thanks are due to Michael Philcox who IQUA Committee organised both the autumn symposium and the Both Pete Coxon (Chair) and Susan Hegarty spring meeting this year. (Secretary) have served their four-year term in office. Nominations were sought first for chair IQUA held a very successful joint fieldtrip with the Michael Philcox proposed Steve McCarron for IAH to North Mayo late last year (see NS 33). It was Chair. The nomination was seconded by Susan noted that this is the second year without a Hegarty. Steve was appointed Chair. fieldguide and it is hoped to redress this in the Nominations for secretary were subsequently coming years. looked for. Steve McCarron nominated Robin Edwards. Pete Coxon seconded. Robin was The autumn symposium “Atlantic Coastal and appointed secretary. Offshore Quaternary: Deposits, Sea-Level Changes and Archaeology” also went very well. There was The committee, as of the end of the AGM was: an excellent attendance for the second year in a Steve Me Carron (Chair) row, with 75 - 80 in the audience at any one time. Michael Philcox (Treasurer) 1 IQUA Newsletter April 2005 Robin Edwards (Secretary) northwards. The magnetic data indicates the Catherine Dalton (Newsletter editor) presence of an igneous body in the west which Paul Dunlop (Publicity officer) dips underneath the landward Carboniferous Tony Brooks (Postgrad representative) sediments. This body appears to outcrop in the Mike Simms far north west of the survey area. Its morphology Susan Hegarty and fracture patterns indicate it may be granitic. AGM Abstracts Cainozoic development of the Proteaceae in south-western Australia Geophysical insights on the geomorphology Freea Itzstein-Davey and palaeo-landscape of the River Shannon at Geography Department, Trinity College, Dublin Clonmacnoise and offshore west of Kerry Head G. Duffy1, C. Brown1 and K Barton2 South-western Australia is a globally 1 Department of Earth and Ocean Sciences. NUI Galway significant hotspot of plant species diversity, with 2 Landscape Geophysical Services, James St Claremorris Co high endemism and many rare plant species. Mayo Proteaceae (Banksia family) is a major E-mail: gavm duffv@ nuictalway io component of the south-western Australian flora, though little is known about how its diversity 10 years ago the remains of a wooden developed. This prompted an integrated study to structure traversing the River Shannon at investigate changes in the abundance and Clonmacnoise was discovered by underwater diversity of Proteaceae, in south-western archaeologists. They have interpreted it as an Early Australia, by concurrently studying three Medieval bridge crossing dated at 800AD. This sediment sequences of different ages over the discovery led to a project to investigate the Cainozoic and a modern pollen rain study. usefulness of high resolution waterborne Modern pollen-vegetation relationships geophysics for the purposes of underwater in the two Proteaceae species rich nodes of the archaeology. The acoustic techniques of side scan northern and southern sandplains were sonar, swath sonar bathymetry and sub-bottom quantified. It was found that Proteaceous genera profiler (Chirp) were employed. The techniques can contribute up to 50% of the total pollen rain. have enabled the classification of river bed The vegetation and environmental setting during sediments. A profile of esker morphology and the three pivotal periods of the Cainozoic: Holocene, highly variable karst topography upon which it lies Pliocene and Eocene, were investigated. has been constructed. We have identified the Eocene sediment from Lake Lefroy presence of gas, possibly due to the decay of confirmed the presence of a Nothofagus organic material at depths < 10m. dominated rainforest in the Middle to Late The detailed bathymetry map identifies the Eocene. At this time Proteaceae species were at current regime in the Shannon today and goes least as diverse as today, if not more so, some way to explaining the differential preservation contributing up to a maximum of 42% of the total of the wooden post remains. Presented is a pollen rain. This study also identified that possible explanation as to why there appears to be Proteaceae species representation varies across 'missing' posts in the middle of the river. A palaeo- landscape reconstruction using detailed seismic and small lateral distances. Thus as samples varied spatially and temporally, single core samples are bathymetric information suggests that the posts may not sufficient to identify spatial patterns in never have been there in the first place. The Proteaceae or other low pollen producing taxa. analysis of fluvial processes has implications for Some 7.91 cm of laminated Pliocene recognising where the archaeological record has sediment from Yallalie, south-western Australia, been preserved and where it has been destroyed. was also examined. It covers 84 years of record In May 2004, the GSI mapped roughly and confirmed other regional reports that south 1200sq km off the Shannon Estuary as part of it western Australia was covered by a rich Irish National Seabed Survey programme. The vegetation mosaic consisting of heathy and wet bathymetry data shows the location of palaeo- rainforest elements. Although Proteaceae coastlines and bedrock features that could only species were a consistent component of the have been sculpted by fluvial features. There is an pollen counts, diversity and abundance obvious lack of surface sediment despite the fact (maximum of 5%) was low throughout the that this area lies offshore from Irelands largest studied section. sediment carrying river, indicating perhaps that A 2 m core was retrieved from Two Mile strong northerly currents carry sediment Lake, near the Stirling Ranges, provided an early Holocene vegetation history. Geochemical and On the beach reworked sandstone palynological evidence recorded little change, boulders partly cover an organic mud >1 m thick. suggesting the environment of deposition was This may have been deposited in a marsh relatively uniform. Proteaceae species were noted behind a former storm beach on the edge of the throughout the core, though in low numbers, at a alluvial fan, a probable precursor of the extensive maximum of 3.5 % of the total pollen rain. existing back-barrier marsh. The organic mud is Findings of this research indicate that overlain by >60 cm of interlaminated fine, shelly Proteaceae species were an important and gravel, sand and mud, probably deposited at the consistent component of vegetation in south back of a sub-recent storm beach. western Australia over the Cainozoic. It is likely that Within the mountains the steep-sided both changing pollination mechanisms and changes Curraheen valley has been cut deeply into in associated vegetation are important in massive-bedded red sandstone of the Kilmurry determining the dispersal of Proteaceaous pollen. Formation (340 m thick: Pracht 1996). The upper By understanding how the vegetation has changed part of the cliffs consists of the sub-horizontal and developed in south-western Australia, present Lough Slat Conglomerate Formation, which has vegetation can be managed to include intra-specific a horseshoe-shaped outcrop around the valley. variation and ensure the majority of species are This is clearly the source of the abundant conserved for present and future generations to conglomerate blocks within and beyond the enjoy. valley, but no prominent scar, that might be linked with an abnormally catastrophic event, has yet been identified. The valley floor is crossed by a variety of The Curraheen Lobe, Slievemish - giant debris debris deposits, including small recessional flow or what? moraines and large blocky boulder ridges. Near Michael Philcox the head of the valley one such ridge, >12 m Geology Department. Trinity College. Dublin high, extends obliquely down valley from the steep rock wall on the north side, but terminates The Curraheen River flows north out of the before reaching the opposite cliff. It consists of Slievemish mountain front 4 mis SW of Tralee. It is large, clast-supported blocks of sandstone and here at the apex of a large fan-shaped sediment conglomerate, most of which have been body, termed the "Curraheen Lobe', which is c.1.5 transported well out from their initial km across (E-W), has a steep arcuate front some accumulation zone, possibly as prolonged 30-40 m high, and resembles from below a terminal rockfall onto moving ice.