The valley has a fascinating geological basis, with the local mountains being very much older than the surrounding Alps.  The local rock is predominantly limestone but there are also large areas of acid soils. On the higher alpine shelf, which lies behind and above Chalet Marion, there are massive limestone pavements, which are some of the largest in Europe. As one might expect this leads to a wide range of flora, the highlights being numerous orchids and gentians. Flora varies considerably; dependent on soil conditions, height and the time the snows melt. Sheaths of Soldanella and crocus come up through the melting snow, as does the lovely Yellow Star-of-Bethlehem (Gagea Lutea). In the damper areas, we find swathes of Globeflowers (Trollius Europeus) and in one valley Primula Farinosa is locally dominant; there are also huge clumps of Oxlip (Primula Elatior). The giant Yellow Gentian (Gentiana Lutea) is common, although it is easy to confuse with the False White Hellebore (Veratrium Album), which is also common. Hidden away up one valley is a small group of the Martagon Lily (Lilium Martagon).

Each day we walk out in a different direction and thus manage to visit the maximum number of different habitats. From the top of the Col de Colombiere, we look down towards the north across the village of Le Reposoir where Chartreuse used to be made.  Now it is better known as the site where the Lammergeier (Gypaetus barbatus), was reintroduced into Europe some 20 years ago. With a wingspan, which reaches 2.9 metres, this is the largest bird in Europe and is a marvellous sight as it glides around the adjacent peaks.

If we walk up from the top of the Col, we expect to find Bouquetin and occasionally spy a family of the rather endearing marmots.