Mapping the Earth's Crust
OF MAPS ARE AVAILABLE AS TIF FILES ON REQUEST: HR15@LE.AC.UK
from the University of Leicester and the University of Cambridge have produced
the first maps of the structure of the deep crust beneath the UK, which will
lead to a better understanding of the geological evolution of the British Isles.
earthquakes that affect Scotland are seen as the result of the retreat of ice
sheets about 8,000 years ago, geologists do not yet understand the cause of many
of the earthquakes occurring in England and Wales, which tend to occur at deeper
levels in the Earth’s crust.
Richard England of the University of Leicester Department of Geology said: “It
is hoped that the new study by Leicester and Cambridge scientists will lead to
an understanding of the cause of these earthquakes, and therefore to the ability
to predict where they will occur. This
would be a useful advance in hazard prediction, since the present record of
earthquake locations appears almost random and is difficult to relate directly
to known faults at the near surface of the earth.”
Above map shows the thickness of the lower crust beneath the UK through which seismic waves travel at a velocity greater than 7 km/s. Because these rocks are less dense than the underlying mantle they caused the surface to be uplifted, producing a source of sediment which was washed into the North Sea and West of the UK and Ireland where it formed the sedimentary rocks which are now reservoirs for oil and gas.
maps have been drawn from deep seismic surveys using technology developed with
the oil industry over the past 20 years. While research is still at an early
stage, and data need to be refined and predictions tested against other
observational evidence, key findings so far indicate that erosion and formation
of the Earth’s landscape are – long term – controlled by the evolution of
the deep crust as well as surface processes.
well as providing a new way of understanding the geological evolution of the
British Isles, the research is assisting the petroleum industry in discovering
natural resources more effectively and safely.
Earth’s crust floats on the underlying asthenospheric mantle, rather like an
iceberg on the sea. The density of the
crust determines the height of the land above sea level.
Long term changes in the density of the crust can contribute to rising
and falling relative sea levels.
studying the surface geology of the UK have known for some time that the
northern and western regions of the UK rose by as much as 500 metres about 60
million years ago, when Europe separated from Greenland to form the Atlantic
now, what was not well understood was the exact cause of this surface uplift.
The new maps produced by the Leicester and Cambridge geologists indicate
that it was caused by magma trapped in the lower crust.
This solidified to form a high density igneous rock, but some rose to the
surface to feed volcanoes, the extinct remains of which are now the islands of
Skye, Rum and Mull in the Inner Hebrides.
TO EDITORS: Further
information is available from Dr Richard England, University of Leicester
Department of Geology, telephone +44 (0)116 252 3795, facsimile +44 (0)116 252
3918, email email@example.com
This document has been approved by the head of department or section.