‘The potential for developing an annually-resolved chronology of events in Scotland during the last glacial-interglacial transition (16-8 ka BP)’. / Macleod, Alison.

2010. 514 p.

Research output: ThesisDoctoral Thesis

Unpublished

Abstract

This thesis focuses on investigating the timing, rates and duration of key shifts in climate during the period 16,000 to 8,000 years ago. Publication of the Greenland Ice Core records has demonstrated the occurrence of abrupt climatic transitions, occurring on decadal timescales, during that period. How rapidly they were propagated, however, and how precisely they can be dated in marine and terrestrial records, is a matter of contention. Conventional chronological tools (e.g. radiocarbon dating), used to date the timing and duration of past climatic events in marine and terrestrial records, lack the precision necessary to constrain the timing of the onset and end of short-lived events such as the Younger Dryas stadial. This research project was initiated to establish the potential for developing more precise chronological tools to advance the study of this important period. In carrying out this research, a range of established (thin section, image analysis) and novel (μ-XRF core-scanning) techniques were adopted to assess laminated sediments for presence of annually-laminations (varves). Where varved records were detected, results were developed further and integrated using independent methods such as tephrochronology and radiocarbon dating within a Bayesian-based age modelling approach.
In total, eight sequences containing evidence of glaciolacustrine deposition were explored from sites located around the inferred margins of the Loch Lomond Readvance ice cap in Scotland. Six of these preserve annually-laminated sediments and two have been investigated in detail: Glacial Lake Blane, Stirlingshire and Loch Laggan East, Inverness-shire. The results indicate that Glacial Lake Blane existed for a minimum of 259 ±3 years directly following deposition of an organic layer dated to between 12,117 and 11,650 cal yrs BP (at 2ζ uncertainty). Loch Laggan East existed for 509 ±4 years, its onset dated to between approximately 12,300 and 12,090 cal yrs BP. The absolute ages of the latter series is constrained by two independently-dated and discrete tephra horizons, one of which can be correlated to the Greenland (GICC05) timescale. These data provide the most precise age estimates yet attained for the timing and duration of key events in Scotland during the Loch Lomond Stadial. They suggest that ice arrived at its maximal position later than previously supposed and may have lingered in parts of the Scottish Highlands into the Early Holocene. This project has paved the way for comparing events in Scotland during the Devensian Lateglacial period with those elsewhere in the North Atlantic region, with a sub-centennial precision.
Original languageEnglish
QualificationPhD
Awarding Institution
Supervisors/Advisors
Thesis sponsors
  • Natural Envt Research Council (NERC)
Award date1 Apr 2010
Publication statusUnpublished - 2010

Research outputs

ID: 1659665