Friday 11th May - Sunday 13th May 2012
Leader: Prof Pete Coxon (Trinity College Dublin)
We travel out to the island on Friday afternoon and return early Sunday afternoon. We will have one and a half field days on the island. On the first day (Saturday) we shall explore the eastern and central part of the island concentrating on the way that glacial deposition can be identified and mapped in such an area and also on the Holocene peat deposits and the archaeology of the island and how geological information can help understand the human impact on the landscape. We can discuss the scale and timing of Quaternary events against the marvellous backdrop of a glacially altered landscape. We will also stroll to the lighthouse (weather permitting) to take in the views across the cliffs of Knockmore.
On the Sunday morning we will walk out along the southern coast to view some of the ice-moulded bedrock of the island. Many features of glacial erosion can be seen in fine detail and the group will be able to see first hand the way that glaciers have altered our landscape.
“The relatively small land area of Clare Island contains a marvellous diversity of landscape that it owes to its varied bedrock composition and to the influence of geomorphological processes operating throughout the Quaternary Period. The bedrock topography of the island has been modified and sculpted by glacial erosion and glacigenic sediments drape much of the island’s surface. Two main periods of glacial deposition can be identified, both probably within the Last Glacial Maximum (LGM), and the differing landform elements and associated sediment units are described. Extensive glacial sediments cover the southern coastal area and the north-eastern parts of the island and a distinct pattern of ice flow and depositional environment can be elucidated from the disposition of tills containing identifiable clast assemblages. The formation of drumlinised, limestone-rich, till along the southern part of the island is followed by the rapid decay and disintegration of the ice sheet and the deposition of widespread hummocky moraine across the north-eastern part of the island. The possibility of an island ice mass emanating from a corrie on the flank of Knockmore, during both the LGM and the Late-glacial, is also suggested. The Holocene (or Post-glacial) environmental history of Clare Island is, in part, preserved in numerous peat-filled hollows and peaty soils. A Holocene pollen diagram from the north-east of the island is presented and the development of the island’s former vegetation cover and its disturbance by prehistoric populations is discussed.”
Abstract from: Coxon, P. 2001. The Quaternary history of Clare Island. In: Graham, J.R. (Ed.) New Survey of Clare Island. Volume 2: Geology. Dublin. Royal Irish Academy. Pages 87-112.
For further information on the accommodation available on Clare Island, please visit:
http://www.clareisland.info/accommodation.htm
To register please contact excursions secretary Dan O’Shea by email, excursions@geology.ie
or phone before 5pm, 29th October next.