Doctoral defense in geology - Nína Aradóttir

Doctoral candidate: Nína Aradóttir

Title of thesis: Glacial geomorphology and dynamics of palaeo-ice streams in northeast Iceland

Opponents:
Dr. Anna Hughes, Senior lecturer in Physical Geography, University of Manchester, Dr. Eiliv Larsen, Scientist emeritus, Geological Survey of Norway (NGU)

Advisors:
Dr. Ívar Örn Benediktsson, Research scientist, Institute of Earth Sciences, University of Iceland and Dr. Ólafur Ingólfssson, Professor Emeritus at the Faculty of Earth Sciences, University of Iceland

Also in the doctoral committee:
Dr. Anders Schomacker, Professor of Quaternary geology, Department of Geosciences, UiT The Arctic University of Norway, Dr. Skafti Brynjólfsson, Geologist, Icelandic Institute of Natural History

Chair of Ceremony: Dr. Guðfinna Th. Aðalgeirsdóttir, Professor and Vice Head of the Faculty of Earth Sciences, University of Iceland

Abstract
This thesis describes the evidence of palaeo-ice streams in northeast Iceland. Ice streams within the Iceland Ice Sheet (IIS) had been previously proposed, but limited studies existed on their geomorphology. The aim of this study was to advance the understanding of the geomorphological imprint, configuration, and dynamics of palaeo-ice streams and their development during and following the Last Glacial Maximum by mapping glacial landforms and analyze their internal architecture. The research focuses on streamlined subglacial bedforms (SSBs; drumlins and mega-scale glacial lineations), crevasse-squeeze ridges (CSRs), and ribbed moraines; however, glaciofluvial and ice-marginal landforms, as well as hummocky terrain were also mapped. The distribution and orientation of SSBs reveal four flow-sets of cross-cutting palaeo-ice streams that shifted in time and space, along with ice divides. During the maximum glaciation, ice flow was towards the north, unconstrained by the topography, but became confined to the fjords and valleys as the ice sheet thinned. The CSRs and ribbed moraines indicate ice-stream shutdown following glacier readvances during the Late Glacial. The variance in landform morphology and distribution is used to reconstruct the configuration and dynamics of the ice streams. The results provide new insight into the dynamics of the IIS and palaeo-ice streams within it and are essential for constraining numerical modelling experiments of the ice sheet’s evolution. This research has implications for our understanding of modern and palaeo-ice sheet behaviour during deglaciation and under warming climate, and paves the way for further studies and reconstructions of palaeo-ice streams in Iceland.

About the candidate
Nína Aradóttir was born in Reykjavík 1990 and graduated from Kvennaskólinn í Reykjavík secondary school in 2010. She completed her BSc degree in geology from the University of Iceland in February 2015 but too part of her studies as an exchange student at the University Center in Svalbard (UNIS). Nína completed her MSc degree in Quaternary geology from the UiT Arctic University of Norway in Tromsø and the University Center in Svalbard, where she lived. After completing her MSc degree, she worked as a park ranger at the Environmental Agency of Iceland and the Vatnajökull National Park. She started her doctoral studies in geology at the Faculty of Earth Sciences, University of Iceland, in October 2018. In addition to her studies, Nína has taught part-time at the University of Iceland and worked as a park ranger. Nína was on the board of the Ranger Association of Iceland from 2019 until 2023, thereof as chairman for two years. Today, she works at the Vatnajökull National Park and sits on the board of the Iceland Glaciological Society.