Numerically modelled diapirs that rise into overburdens with viscous
theology produce a large variety of shapes. This work uses the
finite-element method to study the development of diapirs that rise
towards a surface on which a diapir-induced topography creeps flat or
disperses (''erodes'') at different rates. Slow erosion leads to diapirs
with `'mushroom'' shapes, moderate erosion rate to `'wine glass''
diapirs and fast erosion to `'beer glass''- and `'column''-shaped
diapirs. The introduction of a low-viscosity layer at the top of the
overburden causes diapirs to develop into structures resembling a
`'Napoleon hat''. These spread lateral sheets.