Paris Basin

(Northern French Lowland), a hilly plain in northern France, occupying about one-fourth of the country’s territory.

The surface of the Paris Basin rises gradually from the center (near Paris) toward the uplifted areas that surround the plain on the east, south, and west—the Ardennes, the Vosges, the Massif Central, and the Armorican Massif. On the periphery of the Paris Basin is a series of arched, elongated cuesta ridges with steep outer slopes and gentle inner slopes. The elevation of the central part of the basin is about 100 m, and the largest ridges rise to 500 m (primarily in the east and southeast, in Lorraine and Champagne).

The Paris Basin is a trough of a Paleozoic folded base, filled primarily with Jurassic and Cretaceous limestones, marls, chalk, and clays and Paleogenic and Neogenic sandstones, sand, clays, and thin limestone strata, which are bedded at a very gentle angle. In the center of the basin the depth of the limestone bed is 1,530 m. Petroleum and gas deposits have been discovered.

The Paris Basin is drained by a dense network of rivers, most of which belong to the Seine River basin. The rivers are deep and full. In many places the rivers meander, but the valleys usually narrow sharply where they cut through the cuesta ridges.

The basin has a moderate marine climate. The average July temperature is about 18°C, and the average January temperature, about 3°C. Precipitation ranges from 500 to 700 mm a year. The Paris Basin is the chief industrial and agricultural region of France. There are small but numerous groves of oak, linden, beech, and pine, chiefly on the cuesta ridges. The city of Paris is situated in the basin.