Best natural monuments around Osny offer diverse natural landscapes and historical elements. The region features a mix of wooded areas, wetlands, and geological formations. These sites provide opportunities for nature observation and outdoor activities. Osny's natural areas are characterized by their ecological value and accessible trails.
Last updated: May 5, 2026
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I looked for the old chestnut trees, but alas I saw nothing! Maybe I didn't take the right path. But on the side of the GR, a lot of barriers and signs “private property, no entry, traps, etc.,” made me not want to get off the trail!
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This bucolic path runs along the Stors marsh nature reserve. The ground quickly becomes muddy in bad weather and the days following the rain. That said, the setting is beautiful along the rock faces. For the rest, it's a fairly easy single.
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Magnificent natural reserve that this marsh of Stors.
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Here are many chestnut trees dating back more than 300 years. It is seen in their size and in the width of the trunks. They are discovered through the shaded trails of the Butte de Marines. A nugget of the French Vexin!
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Here we have a beautiful view of the Marais de Stors nature reserve, a preserved site in the middle of the forest. We appreciate the density of the greenery. Over the year, you can admire the different colors, like an open-air fresco. It is the only swamp in the region, which makes it a unique place to discover during a running outing.
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Old quarry being restored by the Departmental Council. Place mainly for educational purposes and public awareness The interest of this quarry lies in the geological substrate, formed from the famous sands of Auvers. https://www.valdoise.fr/888-site-geologique-de-l-auversien.htm
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The region around Osny offers several unique natural monuments. Among the most popular are the Singletrack along the Marais de Stors, known for its beautiful setting along rock faces, and the Auversian Geological Site, an old quarry being restored for educational purposes. You can also find the Breathtaking view of the Stors Marsh, offering stunning vistas of the nature reserve.
Yes, the Auversian Geological Site is specifically noted as family-friendly, offering an educational experience about the region's geological substrate. Additionally, the Parc de Grouchy in Osny, while not listed as a highlight, is an expansive park with diverse landscapes, a carousel for children, and accessible walking trails, making it ideal for family outings. Its blend of natural beauty and historical elements provides a varied experience for all ages.
You'll encounter a variety of natural features. The Marais de Stors and its viewpoint highlight marshlands and dense greenery. The Auversian Geological Site showcases unique geological formations from ancient sands. In the Parc Naturel Régional du Vexin Français, you can discover Large Sinkholes, which are collapses filled with water, and the Ancient Chestnut Trees of Butte de Marines, some over 300 years old.
The region is rich in biodiversity. The Marais de Stors nature reserve, for instance, is known for its rich flora and fauna. The Parc de Grouchy, a significant natural monument in Osny, is a haven for wildlife, with 217 plant species (including orchids), 55 bird species (like mute swans, ducks, and coots), 4 amphibian species, 4 reptile species, and various fish like pike. Numerous insect species, including specific longhorn beetles and butterflies, also thrive there.
Yes, several natural monuments in the area have historical significance. The Auversian Geological Site is not only a natural monument but also a historical site, an old quarry being restored for educational purposes. The Parc de Grouchy in Osny also features historical elements such as the Temple of Love and an 8-meter-deep glaciere, with the Château de Grouchy (now Osny's town hall) situated within its grounds, blending history with nature.
The natural monuments around Osny, particularly sites like the Breathtaking view of the Stors Marsh, offer changing colors throughout the year, making them beautiful in different seasons. The Parc de Grouchy is also enjoyable year-round, providing a serene escape. For trails like the Singletrack along the Marais de Stors, be aware that the ground can become muddy in bad weather or after rain, so drier seasons might be preferable for easier walking.
Absolutely! The Osny area is well-suited for outdoor activities. You can find numerous routes for road cycling, mountain biking, and gravel biking. For example, there are road cycling tours like the 'Tour of Vexin' and 'On the Oise at Auvers...' loop. Mountain bikers can explore routes such as 'Banks of the Oise River' or 'Trail in Montmorency Forest'. Gravel biking options include the 'Axe Majeur footbridge' and 'Oise Riverbanks' loops. You can find more details on these activities in the Road Cycling Routes around Osny, MTB Trails around Osny, and Gravel biking around Osny guides.
Yes, the Breathtaking view of the Stors Marsh is specifically highlighted for its beautiful vista of the Marais de Stors nature reserve. This preserved site in the middle of the forest allows visitors to appreciate the density of the greenery and the changing colors throughout the year, like an open-air fresco.
The Singletrack along the Marais de Stors offers a beautiful setting along rock faces and is generally an easy singletrack. However, visitors should be aware that the ground can become muddy in bad weather and in the days following rain. There are also roots to watch out for on descents. This bucolic path runs along a nature reserve known for its rich flora and fauna.
Yes, the Parc de Grouchy is Osny's most notable natural monument. This expansive park, covering 41 to 42 hectares, offers a rich blend of diverse natural environments, including wooded areas, a large pond, and open lawns. It's recognized for its significant ecological value, supporting varied flora and fauna, and provides a serene escape with accessible walking trails.
Yes, the Ancient Chestnut Trees of Butte de Marines are a notable natural monument. Here, you can discover many chestnut trees that are over 300 years old, recognizable by their impressive size and wide trunks. They are found along the shaded trails of the Butte de Marines, offering a glimpse into the region's ancient natural heritage.
The Auversian Geological Site is unique because it's an old quarry currently being restored for educational purposes. Its primary interest lies in its geological substrate, which is formed from the famous sands of Auvers. This site provides a valuable opportunity to learn about the geological history of the region and is considered both a natural and historical monument.


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