This paper reviews different ways potential-field modelling systems represe
nt the 3D structure of the Earth's crust. 3D structures may be represented
by discrete objects, voxels, surfaces or as a kinematic history and each te
chnique provides the user with a different path through the model-building
process and different abilities to honour the available geological and geop
hysical observations. At present, no one system is capable of supporting th
e range of uses for which potential-field data are collected, and one empha
sis for future development is the ability to translate between the differen
t representations that are used. (C) 2001 Elsevier Science Ltd. All rights
reserved.