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The significance and origins of subglacial bedforms

The department of Mathematics and Statistics at the University of Limerick invites you to a seminar by Dr Jeremy Ely (University of Sheffield).

Title: The significance and origins of subglacial bedforms

Abstract: Ice sheets discharge ice through fast-flowing ice streams and outlet glaciers, which form an arborescent pattern flowing from the ice sheet interior toward the ocean. These fast-flowing portions of the ice sheet have low surface slopes, and hence low gravitational driving stresses. Their rapid motion must therefore be a consequence of conditions and processes which occur at the ice-bed interface. Understanding basal processes is therefore crucial for elucidating the response of ice sheets to climate change and determining future sea-level rise. Unfortunately, access the bed of contemporary ice sheets is logistically challenging due to the 100s-1000s of metres of ice that are in the way. To counter this, many have studied the landforms and landscapes left behind by former ice sheets. For example, the action of the last ice sheet to cover Ireland dominates the landscape we see today. This rich geomorphological imprint is comprised of landforms such as drumlins, ribbed moraines and eskers. Despite being studied for over 150 years, the formation of these landforms is still debated, with multiple hypotheses having been suggested.
One approach to resolving this debate has been to study the size, shape and positioning of these landforms. Such observations provide the following insights into subglacial bedform formation:
-Subglacial bedforms are regularly placed throughout the landscape, suggesting they form through a patterning process.
-The probability distribution functions of large samples of subglacial bedform size and shape measurements are log-normal. This has been interpreted to show growth and coarsening during subglacial bedform development.
-At various locations throughout a palaeo-ice sheet, flow events are preserved, recording examples of subglacial bedforms frozen in different stages of development. Information regarding this development is recorded in the probability distribution functions of subglacial bedform sizes.
-Though often thought of as separate entities, commonly distinguished “types” of subglacial bedforms (e.g. drumlins, ribbed moraines and mega-scale glacial lineations) belong to a morphological continuum of forms. This is perhaps indicative of a common formation process.

Rather than a plethora of mechanisms, a unifying theory of subglacial bedform development is required. Such a theory should explain how subglacial bedforms are organised, grow and comprise a size and shape continuum.
Seminar will take place on Tuesday, December 13, at 4pm, in A2-002. Note the special date and time.

If you have any questions regarding this seminar, please direct them to Iain Moyles (061 233726, iain.moyles@ul.ie). A full list of upcoming seminars can be found at http://www.ulsites.ul.ie/macsi/node/48011

Supported by Science Foundation Ireland funding, MACSI - the Mathematics Applications Consortium for Science and Industry (www.macsi.ul.ie), centred at the University of Limerick, is dedicated to the mathematical modelling and solution of problems which arise in science, engineering and industry in Ireland.
 

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