“Land voor Zand,” the sign reads. Ever wondered about the ground beneath your feet here in Amsterdam?
I’m about to share a story about the land reclamation that makes this location and Amsterdam possible. Land voor Zand is built on centuries of ingenious engineering. Amsterdam’s soil consists of many layers. These layers tell a story thousands of years old. The deeper you dig, the further back in time you go.
The top layer is ophoogzand. This isn’t natural. People add it regularly. This ensures the city doesn’t sink and we don’t get wet feet. Below this lies a layer of peat. It is a soggy mix of plant remains that holds a lot of water. You would easily sink into it.
Under the peat, there is zeeklei then another layer of peat. About 12 meters below the canal water is the first sand layer. This is the first stable layer on which to build houses, bridges, and quay walls. In the 16th century, Amsterdammers discovered this hard layer. They drove piles deep enough to reach it.
Until around 1960, houses were built on poles in this first stable sand layer. Bridges and quay walls also stood on these poles. Since the 1960s, houses have been founded on the second sand layer. It lies 20 meters deep. It provides an even firmer foundation. Large, tall buildings such as the Rembrandt Tower rest on the third sand layer. It is a staggering 60 meters deep.
During the ice age a few hundred thousand years ago, glaciers lay near Amsterdam. The shifting land ice created a large basin about 60 meters deep here. Over thousands of years, this basin filled with various soil deposits. The deepest layer is river sand about 50 meters deep. This is the third sand layer. Above that is keileem. It is a mix of boulders, gravel, sand, clay, loam, and erratic boulders. Glaciers carried this layer during the last ice age.
After the ice age, a warm period called the Eemien followed. During this time, a 2 to 3-meter-thick layer of diatomeeën formed. These are single-celled algae with a silica exoskeleton. This layer often contains natural gas. The sea had free rein during the Eemien. A thick layer of sea clay was deposited. Above that was a layer of sand, mostly sea sand. This is the second sand layer. Today, we build all houses and structures on it. The second sand layer lies between 16.5 and 25 meters below sea level.
During the last ice age, the Wechselien, the sea level was so low that the North Sea was dry. One could walk from Amsterdam to London. A tundra vegetation of mosses, lichens, grasses, and dwarf shrubs formed. This vegetation trapped clay and löss particles. Löss is a fine type of sand. Together with clay, it formed a clayey, peaty layer called the intermediate layer. Above that, wind deposited a layer of sand. This forms the ‘first sand layer’. Until the 1960s, bridges and quay walls were built on it.
As the last ice age ended about 10,000 years ago, the frozen ground slowly thawed. The groundwater rose creating extensive marshes and heaths. In this oxygen-poor ground, peat formed over thousands of years. This peat layer is called the basisveen.
As the earth warmed further, the sea level also rose. The North Sea formed between the Netherlands and England. In the west of the Netherlands, the sea broke through gaps in the beach ridges. It deposited a layer of sea clay and sand. This layer is about 8 to 9 meters below sea level and is also called boerenzand. The late medieval Amsterdammers built their wooden houses on it.
Over time, the beach ridges/dunes formed a continuous whole. The sea could no longer break through. No more seawater flowed into the land. Rain and rivers created a lowland with fresh inland waters. These slowly filled with marsh plants. The remains formed a thick layer of peat over thousands of years. We now know it as Hollandveen.
From the 10th century AD, landowners in the West began large-scale exploitation of these peat areas. In the first centuries, the land was used for agriculture. Due to the sinking of the peat, it was only suitable for livestock farming from the 14th century.
In Amsterdam, the sinking of the soil meant that the ground under the houses had to be raised regularly. Formerly with mud, dredging, household waste, and even cowhides. Nowadays with rubble and ophoogzand. The Amsterdam soil sinks by a few millimeters per year. The layer of sand, silt, and rubble used to raise the streets is now several meters thick.
As if this weren’t enough layers, Amsterdam also deals with the channels of the Oer-IJ. The main channel runs from Strandeiland on IJburg to the west, almost to Spaarndam. The problem is that the first and second sand layers are missing there.
So, as you stand here at Land voor Zand, remember the hidden depths and the incredible feats of engineering that support this city. Amsterdam is a testament to human resilience and ingenuity. It shows how we can shape the land to create a thriving metropolis.