Even when you know what you love about a place, it can be difficult to pinpoint what is absolutely specific to that place, and distinguish that from features inherited from the surrounding region.
Les Alpilles can be said to be a geological accident, in sharp contrast with the Northern plains of the Bouches-du-Rhône, and right in their middle.
Yet it is hard to separate them. If you spend some days in these quarters, you find yourself confronted with that accident upon every move. On the other hand, there is great unity in the landscape and the atmosphere across these plains, as well as the Rhône valley itself on the Western side of the Alpilles. As a result, whether you decide to traverse the range from Saint-Remy, North, to Les Baux on its Southern slopes, or to go around via Tarascon, you begin to integrate the range as a magnificent trick, something designed to make this part of the Bouches-du-Rhône perfectly balanced. Rather than an accident, it feels somewhat like the rock near the center of a japanese garden.
Bouches-du-Rhône is the name of a “Departement” (an administrative division comparable to a County), litterally meaning the Rhône’s Mouth, although the river’s delta is located downstream, beginning in Arles. But when you drive South in the Rhône valley, say from Lyon, along with the flow, you cannot miss the radical change that occurs in Avignon. It feels as if the valley widens there, and one enters the Bouches-du-Rhône shortly South of the city.
From Avignon, the Alpilles range is straight South, with the Rhône flowing to the South-West, and what appears, on a map, to be another branch flowing to the South-East, and toward the Côte-d’Azur. Except it actually is the river Durance flowing North-West, to join the Rhône South of Avignon !
( As a motorist, you have to make up your mind North of Avignon, precisely in Orange, between one highway leading to the Pyrénées and another leading to the Southern Alps. )
To summarize, then: the Northern plains of the Bouches-du-Rhône is the vast triangle widening South of Avignon, extending, along the Rhône toward the South-West, to the city of Arles and, toward the South-East, to Salon-de-Provence, with the Alpilles in the middle.
The Bouches-du-Rhône extends further South to include the Rhône’s delta and the Camargue, on the West, and to Marseilles and Aix-en-Provence to the East.