Crau

Crau. The Crau is a vast, arid plain located in southeastern France, within the Bouches-du-Rhône department of the Provence-Alpes-Côte d'Azur region. Historically formed by the ancient delta of the Durance river, it is divided into two distinct areas: the dry, stony "Crau sèche" and the irrigated, agricultural "Crau humide." This unique landscape, characterized by its iconic flatness and pebble-covered surface, serves as a critical habitat for specialized flora and fauna and supports a traditional economy centered on hay production and sheep grazing.

Geography

The plain extends south from the city of Salon-de-Provence to the Golfe de Fos on the Mediterranean Sea, bordered to the north by the Alpilles hills and to the east by the Camarque. Its most defining geological feature is the thick layer of rounded pebbles, deposited by the Durance during the Quaternary period when it flowed into the Golfe de Fos. This formation creates a highly permeable surface, leading to rapid water drainage. The topography is remarkably flat, with elevations rarely exceeding 120 meters, making it one of the largest stony plains in Europe. The landscape is bisected by the Canal de Craponne, a historic irrigation canal built in the 16th century, which delineates the transition from the arid zone to the cultivated pastures.

Climate

The region experiences a classic Mediterranean climate, characterized by hot, dry summers and mild, relatively wet winters. It is notably exposed to the fierce Mistral, a cold, northwesterly wind that sweeps down the Rhône valley, contributing to the aridity and shaping the vegetation. Annual precipitation is low, averaging between 500 and 600 millimeters, with most rainfall occurring during autumn storms. Summer temperatures frequently exceed 30°C, while frosts are rare in winter. This climatic regime, combined with the stony soil, creates a semi-desert environment in the unirrigated sections, presenting significant challenges for conventional agriculture without human intervention through systems like the Canal de Craponne.

Ecology

The dry Crau hosts a unique and fragile ecosystem, often described as a pseudo-steppe, which is home to several endemic and protected species. The sparse vegetation is dominated by drought-resistant plants like aromatic thyme and asphodel, forming a habitat known as "coussoul." This environment supports a rich insect population, including the endangered Crau plain grasshopper, and is a vital nesting ground for bird species such as the pin-tailed sandgrouse and the little bustard. The irrigated Crau, in contrast, consists of permanent grasslands that provide a different ecological niche. The entire area is recognized for its biodiversity, with parts protected under the Natura 2000 network and as a National Nature Reserve to conserve its distinctive avian and entomological communities.

History

Human activity in the Crau dates to prehistoric times, with evidence of pastoralism from the Neolithic era. In antiquity, it was known to the Greeks of Massalia and later the Romans as a barren, windswept area. The poet Virgil referenced its harshness in the Georgics. Significant transformation began in the 16th century with the construction of the Canal de Craponne by engineer Adam de Craponne, which enabled irrigation and the development of the fertile "Crau humide." Historically, the plain was a major corridor for seasonal transhumance, with flocks moving between the Alps and the Camargue. During the Middle Ages, it was a contested borderland and later saw military use, including during the campaigns of the Duke of Guise and as a training ground for the French Army.

Economy

The economy of the Crau is traditionally anchored in agriculture, most famously the production of "Foin de Crau" (Crau hay), a high-quality, Appellation d'Origine Contrôlée (AOC)-certified hay grown on the irrigated pastures and prized by equestrian centers across Europe. Sheep farming for meat, particularly the local "Agneau de Sisteron" label, remains important, sustaining the pastoral landscape. The plain also supports some viticulture and olive cultivation along its edges. In the 20th century, industrial and port development on its western fringe, near Fos-sur-Mer and Étang de Berre, introduced logistics, energy, and steel industries. However, these activities coexist with ongoing conservation efforts to protect the traditional agricultural practices and the unique ecological value of the stony plain.

Category:Plains of France Category:Natural regions of Provence-Alpes-Côte d'Azur Category:Geography of Bouches-du-Rhône