Náttúrufræðingurinn - 1985, Side 70

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SUMMARY
Measurements of frost
weathering processes
by
G.R. Douglas
Menntaskólinn við Hamrahlíð
Reykjavík
Iceland
J.P. McGreevy and W.B. Whalley
Queen's University
Belfast
N. Ireland
Weathering processes such as "frostbursting1'
and "freeze-thaw" are generally considered to
be the result of a volume increase when water
freezes in porespace in rock. Experiments show
that water in such porespace is often super-
cooled and values for freezing point may vary
from -3°C to -7°C. Field measurements of
temperature in fractures in rock show that air
temperature and rock surface tcmperature are
often different at the same time. Clearly air
temperature measurements are not sufficiently
accurate for explaining the freeze-thaw process.
164