The first two reinforced sections of the dike on Marken are nearly finished. By the end of July 2025, these test sections will open for residents and visitors. Then it will be clear how the new dike will look: stone on the outside, and clay with grass later on the inside.
The stones against the dike form the first protection against waves. This prevents erosion. These stones are important for a strong dike that must last for years. Where do these stones come from and why do we use these particular ones?
Dump Stone from Belgium
At the lower part of the dike, at the waterline, dump stone is applied. This is usually limestone. This is also the case on Marken. This limestone consists of millions of years old fossilized shells and deposits. Despite largely remaining out of sight, the dump stones form the first line of defense against the water. When a wave crashes against these stones, the force is significantly reduced before the wave reaches the stones higher up the dike.
Basalt
The layer of stones on the slope of the dike, called stone block, consists of so-called basalt columns. Basalt is a volcanic rock. It is known for its hardness and durability. In the dike reinforcement on Marken, we also reuse the old basalt columns. Stone block helps to weaken waves that hit the dike and prevent erosion of the core of the dike.
By Ship to Marken
Because Dutch limestone is too soft, we source the dump stone for Marken from Belgium. Through controlled explosions, large chunks are released in the quarry. These stones are sorted on-site and transported by ship to the Netherlands. The journey to Marken takes about 3 days. Transport by water is an efficient and sustainable choice for moving large quantities of stone. Once arrived, we dump the stones into the water.
Laid by Hand
Then the real craftsmanship begins: laying the basalt columns on the dike. This is still done by hand: a craft that only a few people in the Netherlands master. The stones are carefully rolled and placed against each other, just as it was done in the past.
Strict Quality Requirements
Both the dump stones and the basalt columns must meet strict requirements. For each part of the dike, we calculate exactly which type, size, and weight is needed. The basalt columns have already proven their strength. They are expected to last another 50 years. The dump stones come with certificates showing that they can withstand frost, thaw, and erosion. This way, we are sure that the dike can withstand the forces of the Markermeer and the Gouwzee.