Already five thousand years ago, agriculture was practiced on the current Onneresch. This has emerged from an analysis of pollen and plant remains found in a prehistoric pingo ruin near Onnen.
He only finalized his research last week. Mark van der Schoot had his nose in the mud for over a year. Figuratively, then: the Utrecht Master’s student analyzed an endless series of soil samples, looking for indications of human activity on the Onneresch. He found pollen pollen from plants that people had been growing there for thousands of years before the beginning of the era.
Prehistoric ‘pingo ruin’ layer by layer recorded what happened around since the late Ice Age
On Saturday, Van der Schoot presented his preliminary findings in Onnen, together with assistant professor and research supervisor Wim Hoek. The scoop was for the northern members of Land van Ons, the citizens’ cooperative that bought 25 hectares of land under Onnen two years ago and now practices nature-inclusive agriculture there.
But the interest of the two earth scientists from the University of Utrecht is not focused on the buckwheat, triticale and hut tentut that Land van Ons now cultivates there, but on the crops that distant, distant predecessors grew there. The pivot of their research: the so-called pingo ruin that was found in the middle of the rural area south of Onnen.
Such a pingo ruin is created in cold landscapes when an ice layer forms under the earth’s surface and expands due to freezing groundwater or seepage water from nearby streams. Such an ice bubble pushes the earth’s crust upwards, creating hills in the landscape.
Drenthe is the epicenter of Dutch pingo ruins, especially between Hunze and Aa
They are still found in western Canada and that is where the word ‘pingo’ comes from. In the native Inuit language, that word means “slow-growing hill.” A pingo ruin forms when temperatures rise and the ice melts so that the ‘roof’ of such a hill collapses, leaving behind a circular pit in the landscape that fills with the meltwater.
The Netherlands also had pingos, but then about 14 to 15,000 years ago, in the late Ice Age. An estimated 2500 ‘pingo ruins’ still bear witness to this. Especially on the edges of river streams, such as on the Onneresch: on top of the Hondsrug and exactly between the course of the Drentsche Aa and the Hunze.
In any case, this area on the border of Groningen and Drenthe is the epicenter of the Dutch pingo ruins, with more than four hundred sites, but what distinguishes the one on the Onneresch from most others is that it has been so well preserved. Actually by accident, say Hoek and Van der Schoot.
On the Onneresch is ‘the most beautiful historical archive in the Netherlands’
Because where the majority of the Dutch pingo ruins have decayed over the course of many centuries, been peat-peated and dug up for peat, the one near Onnen was covered with sand in 1910 by farmers who turned it into meadows and hayfields. Everything that happened in the area before that is safely stored under that layer: “The most beautiful historical archive in the Netherlands,” says the enthusiastic Hoek.
With volunteers from Land van Ons, the Utrecht researchers pricked countless soil samples from the Onner pingo ruins in search of pollen, the silent witnesses of the historical developments in the area. The analysis was a hell of a job. If only to filter the microscopic pollen remains from the mud, but also to count, identify and date them afterwards.
But then you have something. Or rather: Van der Schoot and Hoek have something, namely a cross-section of what has collected layer by layer from the environment in the pingo lake over the course of thousands of years. Van der Schoot found a remarkable number of traces of charcoal in one layer, about five thousand years old, which, according to his analysis, indicates that humans had already started burning the surrounding forests to use the soil as pasture or arable land as early as three thousand years before Christ.
Charcoal traces indicate deforestation from three thousand years BC
The researcher is strengthened in this persuasion by the subsequent younger strata. First sand, which blew into the pingo lake from the deforested land, then pollen from, among other things, barley and buckwheat, the oldest agricultural crops that humans cultivated and which the people of Land van Ons also cultivate on the Onneresch.
Van der Schoot is delighted with his findings. ,,I hope to have a first version of my thesis on paper in mid-April and then hopefully to graduate.” Research supervisor Hoek is optimistic and anticipates publications in international scientific journals.
The scientists hope for further research. Meanwhile, the ‘Ei van Onnen’, as they have dubbed the ruin because of its oval shape, lies safely waiting under a layer of water that accumulates in the pit that has slowly been created again by the settlement of the peat. ,,The best protection you can have”, says Hoek. “I really like that!”