(1) - Institute of Geography, University of Copenhagen, Øster Voldgade 10, 1350 Copenhagen K, Denmark.
(2) - Geological Survey of Denmark and Greenland (GEUS), Øster Voldgade 10, 1350 Copenhagen K, Denmark. (a) Retired.
(3) - School of Geography, University of Plymouth, Drake Circus, Plymouth, PL4 8AA, United Kingdom. (b) Now: School of Geography, Geology and Environment, Keele University.