**Mystical and impressive: the menhirs of Clendy.** Photo: Thomas Weibel

Switzerland’s very own Stonehenge

The menhirs of Clendy are impressive remnants of the Stone Age. Both mystical and mysterious, the standing stones on the southern shore of Lake Neuchâtel take us on a journey back in time to a long-forgotten era.

Thomas Weibel

Thomas Weibel is a journalist and professor emeritus of media engineering.

Located on the southern shore of Lake Neuchâtel, just as you enter the town of Yverdon and only a few metres back from the road, is an impressive formation of 45 standing stones dating back to the Stone Age: the alignements de Clendy. When the first project to correct the waters of the Jura region, carried out between 1868 and 1891, lowered the level of the lake by almost three metres, enigmatic menhirs emerged from the marshes. The man who made the discovery, engineer Charles de Sinner, described first seeing them in an 1887 essay: “At the foot of a small flight of steps on the bank of the lake (generally intended for use by bathers) one comes across three small crystalline blocks, and some 100 metres further away the first large blocks of the main group.”

**Plan of the site, drawn by Charles de Sinner, the man who discovered it, in 1887.** Bulletin de la Société vaudoise des sciences naturelles No. 23

It was immediately clear to Sinner that these were no normal erratics: “The height of most of the stones ranges from 1 to 3 metres, their width from 80 to 150 centimetres. However, a few are more than 4 metres tall. (…) While some of the boulders are set deep into the ground, others appear to have been simply placed there. This fact, along with the evenness of the terrain and the military-style alignment in two rows, led me to believe right from the start that this was a site built by humans.”

The megalithic site then faded into obscurity again for most of the following century. It was not until 1975 that excavation work unearthed the original postholes in which the large stones had first stood and the wedging stones used to hold them in place. The site was examined thoroughly again in 1981, and precisely charted. To prevent the smallest stones from being stolen, they were replaced by copies made of concrete; the originals are now on display at the museum in Yverdon.

Article in the Journal du Jura at the beginning of March 1975, speculating about the menhirs of Clendy. — **Article in the u003cemu003eJournal du Jurau003c/emu003e at the beginning of March 1975, speculating about the menhirs of Clendy.** e-newspaperarchives

The scientific findings yielded a number of surprises. Many of the megaliths, the biggest of which weigh close to five tons, display human-like features: it is possible to make out a head and two shoulders carved into the stone. This means they are not simply boulders, but something more akin to statues. However, it is not clear whether they are intended to portray gods, ancestors, rulers or heroes. Style comparisons with menhirs in Brittany suggest that the alignements date from the period between 4500 and 4000 BCE. The site may have been in use right up to the Bronze Age (2300-850 BCE) ‒ and continually added to throughout that period.

When faced with an unclear meaning and a lack of written records, archaeologists are quick to solve the conundrum by inferring a ‘sacred place’. The site at Clendy may well have been used for ritual activities. But it could also have served as a prehistoric calendar. Knowing the exact positioning and alignment of the stones is crucial to any research. And that is precisely where one of the problems lay: a local construction company had re-erected the stones in 1986, proceeding more on the basis of aesthetic criteria than scientific interest. Fortunately, the data collected in earlier investigations of the site was so exact that it was still possible to reconstruct it in its original form.

**Beautiful and mysterious. We still don’t know exactly what purpose the menhirs in Clendy served.** Wikimedia

There are indications that the moon played a hugely important role in the religious practices of many prehistoric cultures. But, as it travels across the sky, the moon does not follow an entirely consistent trajectory. Because the moon’s orbit around the Earth is tilted by five degrees to the plane of the Earth’s orbit around the sun, the points on the horizon at which the moon rises and sets vary from year to year. However, the angle between the two (northerly and southerly) moonrise and moonset positions is not always the same: the moon’s orbital plane does not stay fixed in space but shifts slightly, and the angle reaches a maximum every 18.6 years, and a minimum 9.3 years later. These most northerly and most southerly moonrise and moonset positions are known as ‘lunistices’ or lunar standstills.

**Was Clendy perhaps a place for worshipping the moon? Stereo image of a full moon. Taken by Professor Henry Draper, circa 1880.** Swiss National Museum

Astronomical investigations have now shown that the two rows of stones at Clendy were laid out at angles of 222 and 246 degrees, and form a kind of natural sightline. They are aligned precisely with the two points on the horizon at which, 6,000 years ago, the moon set at its southernmost extreme every 18.6 years at the ‘minor’ and ‘major southern’ lunistices. If a stargazer had stood at the intersection of the two rows at the far north east of the site and looked over the tops of the stones, when the moon dipped below the horizon they would have been able to tell when exactly either of the two standstills – important events in the prehistoric calendar – was occurring. Researchers have posited that the four outermost stones at Stonehenge near Amesbury in the south of England, referred to as the Station Stones, may also mark a lunar alignment.

So, does this mean that the megalithic site at Yverdon was a temple? Or a Stone Age observatory? Or both? Whatever it was: watching the moon go down at the alignements de Clendy takes us on a journey into the distant past and the very beginnings of astronomy.

More of: Protohistory Nature Culture

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