Alicia Medialdea

Dr. Alicia Medialdea

orcid

Research Focus & Metrics

Academic Career Length

24Years (2003-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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7 September 2022 in Boreas
Verified
Journal Article
Open access
CCChris D. Clark
Chris D. Clark
JEJeremy C. Ely
Jeremy C. Ely
RHRichard C. A. Hindmarsh
Richard C. A. Hindmarsh
SBSarah Bradley
Sarah Bradley
AIAdam Ignéczi
Adam Ignéczi
PWPeter Wilson
Peter Wilson
The BRITICE‐CHRONO consortium of researchers undertook a dating programme to constrain the timing of advance, maximum extent and retreat of the British–Irish Ice Sheet between 31 000 and 15 000 years before present. The dating campaign across Ireland and Britain and their continental shelves, and across the North Sea included 1500 days of field investigation yielding 18 000 km of marine geophysical data, 377 cores of sea floor sediments, and geomorphological and stratigraphical information at 121 sites on land; generating 690 new geochronometric ages. These findings are reported in 28 publications including synthesis into eight transect reconstructions. Here we build ice sheet‐wide reconstructions consistent with these findings and using retreat patterns and dates for the inter‐transect areas. Two reconstructions are presented, a wholly empirical version and a version that combines modelling with the new empirical evidence. Palaeoglaciological maps of ice extent, thickness, velocity, and flow geometry at thousand‐year timesteps are presented. The maximum ice volume of 1.8 m sea level equivalent occurred at 23 ka. A larger extent than previously defined is found and widespread advance of ice to the continental shelf break is confirmed during the last glacial. Asynchrony occurred in the timing of maximum extent and onset of retreat, ranging from 30 to 22 ka. The tipping point of deglaciation at 22 ka was triggered by ice stream retreat and saddle collapses. Analysis of retreat rates leads us to accept our hypothesis that the marine‐influenced sectors collapsed rapidly. First order controls on ice‐sheet demise were glacio‐isostatic loading triggering retreat of marine sectors, aided by glaciological instabilities and then climate warming finished off the smaller, terrestrial ice sheet. Overprinted on this signal were second order controls arising from variations in trough topographies and with sector‐scale ice geometric readjustments arising from dispositions in the geography of the landscape. These second order controls produced a stepped deglaciation. The retreat of the British–Irish Ice Sheet is now the world’s most well‐constrained and a valuable data‐rich environment for improving ice‐sheet modelling.

27 March 2019 in Scientific Reports
Verified
Journal Article
Open access
PDF file
BRBenedikt Ritter
Benedikt Ritter
VWVolker Wennrich
Volker Wennrich
AMAlicia Medialdea
Alicia Medialdea
DBDominik Brill
Dominik Brill
GKGeorgina King
Georgina King
TDTibor J. Dunai
Tibor J. Dunai
Paleoclimate records from the Atacama Desert are rare and mostly discontinuous, mainly recording runoff from the Precordillera to the east, rather than local precipitation. Until now, paleoclimate records have not been reported from the hyperarid core of the Atacama Desert (<2 mm/yr). Here we report the results from multi-disciplinary investigation of a 6.2 m drill core retrieved from an endorheic basin within the Coastal Cordillera. The record spans the last 215 ka and indicates that the long-term hyperarid climate in the Central Atacama witnessed small but significant changes in precipitation since the penultimate interglacial. Somewhat ‘wetter’ climate with enhanced erosion and transport of material into the investigated basin, commenced during interglacial times (MIS 7, MIS 5), whereas during glacial times (MIS 6, MIS 4–1) sediment transport into the catchment was reduced or even absent. Pelagic diatom assemblages even suggest the existence of ephemeral lakes in the basin. The reconstructed wetter phases are asynchronous with wet phases in the Altiplano but synchronous with increased sea-surface temperatures off the coasts of Chile and Peru, i.e. resembling modern El Niño-like conditions.

1 August 2014 in Quaternary Geochronology
Verified
Journal Article
Closed access
AMAlicia Medialdea
Alicia Medialdea
KTKristina Thomsen
Kristina Thomsen
AMA.S. Murray
A.S. Murray
GBGerardo Benito
Gerardo Benito

1 January 2019 in Quaternary Science Reviews
Verified
Journal Article
Open access
VTVaryl R. Thorndycraft
Varyl R. Thorndycraft
JBJacob M. Bendle
Jacob M. Bendle
GBGerardo Benito
Gerardo Benito
BDBethan J. Davies
Bethan J. Davies
CSCarlos Sancho
Carlos Sancho
JMJulian R.V. Martin
Julian R.V. Martin

1 October 2018 in Quaternary Science Reviews
Verified
Journal Article
Open access
DRDavid H. Roberts
David H. Roberts
DEDavid J.A. Evans
David J.A. Evans
SCS. Louise Callard
S. Louise Callard
CCChris D. Clark
Chris D. Clark
MBMark D. Bateman
Mark D. Bateman
TBTom Bradwell
Tom Bradwell

1 November 2019 in Journal of Hydrology
Verified
Journal Article
Closed access
Sergio Martos RosilloSergio Martos Rosillo
Sergio Martos Rosillo
ARA. Ruiz-Constán
A. Ruiz-Constán
ARAntonio González Ramón
Antonio González Ramón
RMRosa Mediavilla
Rosa Mediavilla
JMJ.M. Martín-Civantos
J.M. Martín-Civantos
JDJ.J. Durán
J.J. Durán