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The Western Chartreuse is a magnificent example of an inverted relief: to the east the slopes of large synclines, sheared by rain and then glacial erosion, form a rocky wall rising 1800m/5900ft above the floor of the Grésivaudan Valley. Larger than the Western Chartreuse, the Eastern Chartreuse shelters the main towns on the massif in its broad open landscape valleys, overlooked by numerous hamlets, along the edges of the woodlands that cover its heights. Weather systems from the west run into the Chartreuse, which thus receives abundant precipitation.

A great deal of the meteoric water and snowfall takes advantage of the numerous faults and joints on this massif, so marked by its turbulent tectonics, to seep downwards. The underground water dissolves the limestone and runs through a vast system of underground caves and galleries. Cascading waterfalls and streams are fed as water runs against impermeable layers and exits from the cliffs.

The history of the central valleys of the Chartreuse was marked by fluctuations in the border between France and Savoie, in particular in the Entremonts Valley. The traditional economy is based on forestry, which is still an important activity, and on livestock raising (dairy) on the Alpine meadows.

The Chartreuse, which, unlike the Vercors, does not have any major resorts for downhill skiing, is well suited for the development of tourism based, on the one hand, on the discovery of nature and the cultural and architectural heritage, and, on the other, on open-air sports like mountain biking, cross-country skiing, potholing, paragliding, etc.

This development has been encouraged by the creation of the Parc naturel régional de la Chartreuse in 1995.

The Central Valleys

Typically pre-Alpine landscapes : these are the landscapes crossed by RD 512, 102 B and 912 , the direct links between Grenoble and Chambéry, which avoid the detour through the gorges of the two Guiers rivers between Saint-Pierre-de-Chartreuse and Entremonts.

One noteworthy feature is the general orientation of the two valleys , which follow on one another in a north eastern-southwestern direction characteristic of the Chartreuse massif and the Vercors massif. This orientation stands out from the strong points that punctuate the itinerary over thirty kilometres/19 miles: the passes at Vence, Palaquit, Porte and Cucheron in Isère, and the Col du Granier, in Savoie, which are themselves punctuated and accompanied by the emblematic summits and ridges that link them: to the east, Chamechaude (2082m/6831ft), the Roc d'Arguille (1768m/5800ft), the Crête des Lances de Malissard (1981m/6499ft) and, in Savoie, Granier (1933m/6342ft), and to the west Pinéa (1771m/5810ft), Charmant Som (1867m/6125ft), Grand Som (2026m/6647ft), Roche Veyraud (1429m/4688ft) and, in Savoie, the Outheran chain (1676m/5499ft). This dominant orientation is further highlighted by the forest treelines, which themselves delimit the meadow clearings and villages.

Their ambient characteristics are also determined by the handling and location of building features. A square-style architecture, with hipped roofs ("toits à quatre pans") characterises the groups of homes gathered around a central core. Saint-Pierre-de-Chartreuse is pressed against the hollow of the valley. The church and the surrounding buildings form an impressive façade, particularly when seen from the stream below. Some fifty nearby hamlets are distributed at regular intervals of about 500 metres/one-third mile in the surrounding open space, and often bear the names of the first families to set up home there: the Revols, Guillets, Michalets, Cottaves, etc. As for Saint-Pierre-d'Entremonts ,it is the Alps themselves that harbour its unique secret: two twin communes each with its own church, on either side of the Guiers Vif, stand as a tangible symbol of the historic battles fought over this territory between the Houses of Savoie and Dauphiné. But other nearby hamlets that take the names of Vincent, Tardy, Teppaz, Rigauds and Perrets also reflect, in the order in which they are spaced, membership in a single mountain culture, the same as that of the other Saint-Pierre. This is a culture marked by an economy centred on the family unit, managing the surrounding land through daily, arduous labour.

Another characteristic typical of the pre-Alps is the transformation of this traditional economy into one based on attracting a wide variety of groups of people who are attracted by its strong points, which in olden times were points of concern: the network of country lanes and trails, including the GR 9 hiking trail and those of the Touring Club . These footpaths and trails are major landscape features, both because of their design, which glues them right to the reliefs, and because of the vistas they provide over the surrounding landscapes.

The Guiers Mort and Guiers Vif Valleys

The D 520 b and 520 c, give access to the centre of the massif from the west to the east and through the converging gorges. And while the lanes and trails are among the major features of these valleys, here it is the roads and their civil engineering structures that rival the other major landscape attractions in interest.

The two valleys run in the same direction as the Vence Valley, but are longer and have only two villages of any size, the two Saint-Pierres. In the other directions, it is the gorges that enable the roads to cross the major synclinal barriers, with their steep limestone slopes, their dense forests, and the two unique sites of the cirque de Saint-Même, on the Guiers Vif, and the Vallon du silence in the Désert de la Grande Chartreuse.

One wonders how there is room for roads among gorges so deep, narrow and encased. These often vertiginous gorges, like those in the Vercors, became emblematic of the opening they provided for discoverers of landscapes at the end of the last century and for the enthusiasm that they aroused. This is still true today.

The Pas du Frou on the Guiers Vif: in the local dialect, the "terrible" pass. Hence the emblematic character of its spectacular reversal of the perception of the mountain landscape, considered for centuries as "terrible lands" and today as "gigantic" landscapes, since the "sublime" is no longer part of current discourse. The Pas du Frou over the Guiers Vif, the Pas de l'Oeillette over the Guiers Mort and all the civil engineering works, tunnels, bridges and other cantilevered passageways, these masterpieces of functional aesthetics, are the source of an exceptional landscape motivation. They represent the capacity of human creativity and construction to overcome obstacles, but without destroying them – in fact, by working in composition with them and accompanying them in the most natural fashion. The road thus fits in with the features of a relief that those using the road discover as they advance. The same is true for the crossways profile, which is calculated in close relationship to the steepness of the drop, maintaining a slight tension as one carefully advances, even in the best traffic conditions. The same also holds true of the materials used in the construction, which are based on the nature of the place.