TY - JOUR
T1 - Ice streaming and the demise of the Last British Ice Sheet: geomorphological evidence, modelling experiments, and cosmogenic nuclide chronology
AU - Bradwell, T.
AU - Hubbard, A.
AU - Fabel, D.
AU - Golledge, N.
AU - Stoker, M.
AU - Everest, J.
AU - Finlayson, A.
AU - Howe, J.
PY - 2010/12/1
Y1 - 2010/12/1
N2 - We synthesise recent work on the palaeoglaciology of the British-Irish
Ice Sheet, focusing on the glacial geomorphology preserved on the seabed
around the northern UK [Bradwell et al., 2008]; and a suite of numerical
modelling experiments spanning the last ~40 ka [Hubbard et al., 2009].
In addition, we present a new temporal dataset to better constrain the
decay of ice stream sectors within the last British Ice Sheet. Our suite
of cosmogenic exposure ages dovetails well with the emerging view
recorded in other environmental proxies. Modelling experiments, forced
by NGRIP ice-core data, show an extremely dynamic ice sheet drained by
transient but recurrent ice streams which dynamically switch and
fluctuate in extent and intensity on a centennial time-scale. Our Be-10
cosmogenic chronology sheds new light on the timing of ice stream
activity and cessation, placing the separation of the British and
Fennoscandian ice sheets at ~24 ka BP - closely associated with the
iceberg discharge event Heinrich-2. In the NW sector, the Minch Ice
Stream, a quasi-stable feature of the last British Ice Sheet, probably
scavenged ice from an adjacent catchment shortly before its demise c. 18
ka BP. In the NE sector, a large ice stream in the Moray Firth continued
to operate until c. 15 ka BP - whereby model simulations show a rapid
collapse, within the space of 100 yrs. Ultimately, the resolution of
such short-lived events lies within the uncertainties of currently
available dating techniques. Hence, further high-temporal resolution
studies are required to explore the role of internal (glaciological) vs
external (eustatic and climatic) forcing on the stability of ice streams
within marine-terminating ice sheets.
AB - We synthesise recent work on the palaeoglaciology of the British-Irish
Ice Sheet, focusing on the glacial geomorphology preserved on the seabed
around the northern UK [Bradwell et al., 2008]; and a suite of numerical
modelling experiments spanning the last ~40 ka [Hubbard et al., 2009].
In addition, we present a new temporal dataset to better constrain the
decay of ice stream sectors within the last British Ice Sheet. Our suite
of cosmogenic exposure ages dovetails well with the emerging view
recorded in other environmental proxies. Modelling experiments, forced
by NGRIP ice-core data, show an extremely dynamic ice sheet drained by
transient but recurrent ice streams which dynamically switch and
fluctuate in extent and intensity on a centennial time-scale. Our Be-10
cosmogenic chronology sheds new light on the timing of ice stream
activity and cessation, placing the separation of the British and
Fennoscandian ice sheets at ~24 ka BP - closely associated with the
iceberg discharge event Heinrich-2. In the NW sector, the Minch Ice
Stream, a quasi-stable feature of the last British Ice Sheet, probably
scavenged ice from an adjacent catchment shortly before its demise c. 18
ka BP. In the NE sector, a large ice stream in the Moray Firth continued
to operate until c. 15 ka BP - whereby model simulations show a rapid
collapse, within the space of 100 yrs. Ultimately, the resolution of
such short-lived events lies within the uncertainties of currently
available dating techniques. Hence, further high-temporal resolution
studies are required to explore the role of internal (glaciological) vs
external (eustatic and climatic) forcing on the stability of ice streams
within marine-terminating ice sheets.
KW - 0730 CRYOSPHERE / Ice streams
KW - 0774 CRYOSPHERE / Dynamics
KW - 0776 CRYOSPHERE / Glaciology
KW - 0798 CRYOSPHERE / Modeling
M3 - Article
VL - 51
JO - American Geophysical Union, Fall Meeting 2010, abstract #C51B-03
JF - American Geophysical Union, Fall Meeting 2010, abstract #C51B-03
IS - 3
ER -