Tertiary isohypse top

The isohypse maps are part of the Quartair and Tertiary maps of Flanders. Isohypses represent the relief of the base of the Quaternary deposits, which is the same as the top of the Tertiary deposits. The contour lines form an overlay of the lithoprofileytpe maps. The systematic mapping of the Quaternary and Tertiary geological layers on a scale of 1:50000 in Flanders, commissioned by the Flemish Region, was started in 1993. For a more detailed description see https://www.dov.vlaanderen.be/page/quartair