Historical geography — clay extraction

Historical record of sites where clay extraction has taken place in history. The areas suitable for clay extraction were plotted (about 60 centimetres on average) and thus their ground level was greatly reduced, making them well recognizable in the landscape, between the un dug higher plots. Several hundred hectares of clay land must thus have been excavated over the centuries. Clay extraction along the (former) sea dikes is related to various phases of dike construction and reinforcement, for which the required clay was stabbed in the immediate vicinity as much as possible. Some of these ‘dyks-delten’ or dike wells are currently under management as a nature reserve.