Testing climate synchronicity between Scotland and Romania since the last glacial maximum

Gheorghiu, Delia Mihaela (2012) Testing climate synchronicity between Scotland and Romania since the last glacial maximum. PhD thesis, University of Glasgow.

Abstract

This thesis develops a chronology of ice retreat in the Monadhliath Mountains (Scotland)
and Rodna Mountains (Romania) during the late Pleistocene using glacial geomorphology
and surface exposure dating with cosmogenic 10Be.

In the Monadhliath Mountains, 10Be exposure ages indicate deglaciation of the Last
Devensian ice sheet at 15.1 ka (n = 2). Boulders from moraines in three Monadhliath
cirques yielded exposure ages between 11.8 ka and 9.8 ka (470 – 600 m), suggesting that a
Late Glacial readvance occurred during the Younger Dryas stadial (n = 9). The limited
extent of these YD glaciers in the Monadhliath Mountains is explained in terms of the drier
climate experienced by the eastern part of the Central Highland ice cap, but also in terms
of local factors such as topography and snow blow. The resulting glacial reconstruction
largely confirms that a SW to NE precipitation gradient dominated Scotland during the
Younger Dryas.

In the Romanian Carpathians, located at the southern periphery of the NW European ice
sheet, there was only limited coverage of ice, mostly at higher elevations in the form of
mountain glaciers. Field evidence suggests that during the last local maximum glaciation
ice reached lower elevations than previously suggested in the Rodna Mountains. Glacially
transported boulders were abandoned at 37.2 – 26.6 ka (n = 4) at an elevation of ~900 m.
Glacial erratics and bedrock samples (n = 27) provide a consistent chronology for
deglaciation during the Lateglacial, suggesting that ice retreated towards higher ground
between 18.3 – 13.2 ka (1100 – 1800 m altitude). Final deglaciation took place at 12.5 -
11.2 ka (n = 9).

These new chronologies are compared to other climate archives in Europe and the climatic
oscillations recorded in the North Atlantic region. This analysis increases our
understanding of past atmospheric circulation across Europe, and gives insights into the
climatic forcing mechanisms during the last maximum extent of ice sheets and glaciers.
During the last glacial episodes, the pattern of climate cooling from the western high
latitudes towards the eastern mid latitudes was complicated, triggering different responses
in local climates that appear to have been out of phase with the broader north-western
European trend. Located in the NW Europe, Scotland was influenced by the wetter and
colder conditions from the Atlantic which led to the expansion of the British Ice sheet
during the global Last Glacial Maximum (LGM). However, smaller ice masses located
further southwards and south-eastwards of the European ice sheet responded faster to the
climatic oscillations in the North Atlantic region. During the LGM, the southward
repositioning of the Polar Front and the presence of the ice sheet changed the atmospheric
circulation across Europe. There was limited supply of moisture to the Rodna Mountains,
especially because of blocking by the eastern Siberian high pressure system, and the
glaciers experienced a slow retreat in a very cold and dry environment. However, a more
synchronous Younger Dryas is likely to have occurred due to a more northern position of
the Polar Front. This allowed for stronger wet and cold westerly winds to reach most of
Europe at the same time.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Additional Information: Parts of Chapter 4 have been published online: D.M. Gheorghiu, D. Fabel, J.D. Hansom, S. Xu, Lateglacial surface exposure dating in the Monadhliath Mountains, Central Highlands, Scotland, Quaternary Science Reviews, Volume 41, 18 May 2012, Pages 132-146, ISSN 0277-3791, 10.1016/j.quascirev.2012.02.022. (http://www.sciencedirect.com/science/article/pii/S0277379112001102)
• Keywords: Last Glacial Maximum, Younger Dryas, Devensian glaciation, surface exposure dating, geomorphology, Monadhliath Mountains, Rodna Mountains, Scotland, Romania.
• Subjects: G Geography. Anthropology. Recreation > GB Physical geography; G Geography. Anthropology. Recreation > GE Environmental Sciences
• Colleges/Schools: College of Science and Engineering > School of Geographical and Earth Sciences
• Supervisor's Name: Fabel, Dr. Derek
• Date of Award: 2012
• Depositing User: DM Gheorghiu
• Unique ID: glathesis:2012-3362
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 14 May 2012
• Last Modified: 03 Jun 2015 07:22
• URI: https://theses.gla.ac.uk/id/eprint/3362