Nez de Boeuf-Roche Plate (rivière des remparts)

Hiking in the valley of the Rivière des Remparts helps you better understand how Reunion Island was formed and the history of how the Highlands were settled. Beyond the beauty of the landscape, it’s interesting to be accompanied by someone who understands volcanism and how the region was settled to better understand the island. The hike starts at the volcano massif at the point known as Nez de Boeuf. You’ll begin to descend the ramparts to the bottom of the valley and then follow the gently sloping path that takes you to the islet of Roche Plate. The descent of the rampart offers a bird's-eye view over the valley, while the second part of the route takes you through a real tropical forest to Roche Plate. If you decide to go down to Saint-Joseph. Here is some information about the formation of the Rivière des Remparts and how the valley was settled. 290 000 years ago, a major collapse occurred in the area of the Rivière des Remparts, then the heavy rainfall began to carve out the valley, and the unstable ramparts collapsed. More than 60 000 years ago, lava flows partially filled the valley, until the Pas des Sables incident, which then isolated definitively the area of the Rivière des Remparts from the active centre of Piton de la Fournaise. Erosion resumed and dug out the valley again. Two thousand years ago, an eruption occurred along a fissure alongside the Rivière des Remparts, producing three new craters. Commerson more than 200 m deep, Trou Fanfaron located below Commerson on the left rempart of the Rivière des Remparts, and lower down a third cone, much less visible. The lava flows from these three craters made their way down the valley to Saint-Joseph, 22 km downstream, reaching the ocean to form Pointe de la Cayenne. Like what had happened earlier in Bébour, these lava flows gave the valley of the Rivière des Remparts its flat, sloping bottom as we know it today. The settlement of the Rivière des Remparts happened in the same way that the cirques were settled.
The first inhabitants of the Rivière des Remparts were runaway slaves also called "Marrons", followed by a few whites from the highlands, mostly from Saint Joseph. They settled in different islets including Roche Plate and Dimitile. Roche Plate was the main one and counted up to 600 inhabitants in 1965. They grew peas, beans, sweet potatoes, peaches, loquats, coffee, vetiver and maize and raised pigs, goats, poultry and oxen in the grazing areas above Roche Plate. You can still see the low walls that marked out the parcels of land. The Mahavel disaster put an end to the settlement of the Rivière des Remparts on 7 May 1965. The Journal of Reunion Island of 7 May 1965 reports the landslide that occurred at 4 o'clock in the morning 1.5 km downstream of the village of Roche Plate. ‘The prefectoral authorities took the necessary measures to evacuate the 45 families living in Roche Plate and temporarily relocate them to Plaine-des-Cafres or Saint-Joseph. In fact, most families had left their modest homes of their own accord soon after the collapse of the mountain, a phenomenon accompanied by a tremendous explosion, followed by an endless series of deafening rumblings, while huge quantities of sulphur steam spread across the valley. The inhabitants of Dimitile recall: 'It was hot ash-coloured mud, smelling of sulphur... With the barrage, we could no longer see Roche Plate'. In the night, with the fog and rain, the inhabitants of the valley believed a volcanic eruption was taking place and fled.’ The unstable rampart of Bras de Mahavel broke away and several million cubic metres of rocks and mud blocked the Rivière des Remparts. In this way, a lake was formed, which emptied gradually. The following year, the heavy rains that accompanied the passing of Cyclone Denise created another immense lake. The authorities decided to dig a channel at the foot of the western rampart to empty the lake, thus limiting the risk of flooding to Saint Joseph in the event of a rupture of the dam created by the catastrophe the previous year. Scarred by this catastrophe, which fortunately did not result in any casualties, Roche Plate remained uninhabited for 18 years. But in 1989, the ONF (National Forestry Office) undertook reconstruction work to the islet of Roche Plate and several families resettled there, including two gites (lodges).

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