It consists of marine limestones, shales, marls and clays. The Late Eocene reflects more frequent lateral variations of interbedded limestones, dolomites, marls, and shales. During the lower Aptian, sandstones, shales, sandy marls, and limestones were laid down. The Chalk Group consists of a sequence of chalky limestones with some interbedded marls. The Lower Muschelkalk consists mainly of limestone, calcareous marls and clayey marls. The upper Aptian and the Albian are mainly marls and limestones. In Flanders, sands, gravels and marls predominate, covered by silts in places. This source rock is composed of marls and organic rich laminated shales. It may occur as an authigenic mineral in shales and marls. The whitish colouring is because of the quartzose, sandstone and marls, rich in calcium carbonate. It is defined above and below by layers of yellowish marls. These were backfilled with the weathering marls from the immediate area. Ironside is married to Karen Marls Dinwiddie. The turning point in Marls history was 21 January 1875. The one-time Keuper Marls are now redesignated as the Mercia Mudstone Group.