How Mont-Saint-Michel Resists All Rising Tides

In October of last year, something happened to the mainland commune (French civil township) and UNESCO World Heritage Site on Mont-Saint-Michel that showed that decades of conservation efforts were finally paying off.

Namely: it flooded.   

Or rather, the bridge connecting it to the mainland did, due to an unusually high tide (over 14 metres in height/depth). It’s a rare sight, and a truly spectacular thing when it happens, almost supernaturally photogenic, like a Disney special effect coming to life in the real world. When it happens, it completely disconnects the town from the mainland, turning France’s perhaps most famous fortified town (except with an abbey, not a castle) into a tidal island.

You might think the locals would be peeved about this – but it’s exactly what France wants from Mont-Saint-Michel, and always has. 

Mont Saint-Michel at low tide
Mont Saint-Michel at low tide

In a world of rising sea levels, the challenge will certainly be to keep this magnificent landmark above water, but going too far would prove just as unacceptable. Its magic comes from being in perfect equilibrium amidst the tides of history (literally and figuratively)…and nobody wants that balancing-act to end. 

Seen from afar, it’s easy to forget this isn’t a man-made thing. Yes, every inch of its 7 hectares now seems to be festooned with buildings in the most delightfully higgledy-piggledy way, but nothing humans could have made would have endured this long without the igneous rock underpinning it. In prehistoric times, this stretch of the French coast was landlocked.

As the world warmed and the sea crept in, it nibbled away everything around this outcrop of hard, pale granite-like rock, leaving it high and exposed while everything else was dissolved and carried away. 

Such an impressive, easily-defended position wouldn’t have escaped the notice of prehistoric peoples of the region – but its most recent lifespan started when, as legend has it, the archangel Michael appeared to the bishop of nearby Avranches and ordered him to ascend the rock (then called Mont Tombe) to build a church there.

The island’s human history from this point is one of dignified resilience. It appears on the Bayeux Tapestry – the woven account of William of Normandy’s successful conquest of England in 1066. It features in a succession of battles of many periods, always as an impregnable stronghold (during the Hundred Years War, 1337–1453, the English repeatedly attacked it and were successfully repulsed every time).

When France turned on itself during its Wars Of Religion (1562–98), exactly the same happened – and its splendid, impregnable isolation was weaponized by Napoleon I, who turned it into a prison until 1863. Mont-Saint-Michel may have been a centre of holiness in Europe, but it wasn’t a place that offered easy plunder to the raiders that plagued holy sites elsewhere.

It would take an irresistible wave of mechanised humanity, in the form of the might of the German Army, to swamp Mont-Saint-Michel. They took the town on the 18th June 1940, and would hold it for four long years, keeping the conquered population firmly at bay (during this time, over 325,000 Germans visited as tourists, while just 1,000 French visitors were allowed access). 

View of the tidal flats from Mont Saint-Michel
View of the tidal flats from Mont Saint-Michel

When the tide of the War turned and the Allies swept west after D-Day (June 6th 1944), the Germans abandoned the town largely without a fight (although one soldier attempted a literal parting-shot by emptying his machine-gun into the statue of the abbey’s founding bishop, presumably in a fit of pique).

The honour of claiming Mont-Saint-Michel for the invading American forces would go to one Private Freeman Brougher, of the 72nd Public Services & Psychological Warfare Battalion (a propaganda unit). With a couple of journalists riding beside him, Brougher drove across the then-causeway to the island to be greeted with rapturous applause, flowers, champagne and a fusillade of kisses from local girls.

After signing the commune’s Golden Book, a visitor’s book usually only rolled out for royalty, the “savior of Mont-Saint-Michel” (as he would later describe himself to his daughter) nobly stepped back into the ranks, the town’s French inhabitants started changing German signage back into French, and normality returned once more.

It’s only recently that the island’s greatest existential threat has made itself known – and it’s come, as mirrored so frequently elsewhere, from its own popularity.

At low tide, it’s currently possible to walk around the entire island – if (and this is a significant “if”) you employ the services of a local guide who knows how to avoid quicksand and spot the signs of a deceptively quick tide creeping back in. But it’s possible. For part of its lifecycle, it’s surrounded by land – making it a place that teeters right on the brink of becoming part of the mainland, and exacerbated by a tide that’s stronger coming in than it is going out, thereby dumping more sediment than it takes away. 

In an attempt to make the town more accessible by building a raised causeway in 1879, French planners inadvertently gave the incoming sand more of a purchase, by blocking the tide’s path of sweeping incoming sediment back out to sea.

The silt started to build up, the spit of permanent land reached out from the shoreline towards Mont-Saint-Michel – and suddenly, after centuries of warding off almost every threat that came its way, it looked like the island had finally met a foe it had no chance of resisting.

At last seeing this threat, France’s government has stepped up in a big way. First it constructed a hydraulic dam on the Couesnon River, which the town sits at the mouth of. Using carefully-timed pulses of released water, the dam helps wash sediment back out to sea – and in 2014, this was helped along by the replacement of the most recent version of the town’s causeway with a bridge, with the space below it to allow easy passage of the silt as the tide drags it out. 

A majestic monument between land and sea
A majestic monument between land and sea

To be sure, these are last-ditch attempts to save the island – without them, it’d be landlocked within 30 years – but they’re working, and the French government has committed to spend a total of 130 million Euros on the whole restoration project over the next decade. Its enduring status as an island seems confirmed (which must be a relief to its 30 full-time inhabitants, as tourism is almost the sole source of income).

For now, and perhaps for centuries to come, the balance is again restored. It’s a place that sits resolutely between sea and solid ground, refusing to commit itself to either. “Here I stand, just as I always have,” it says – and for now, nothing seems capable of arguing otherwise.

Wheel & Anchor will be visiting Mont-Saint-Michel in October 2022. Join us!

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