The other principal river, the Aisne, crosses the southern border and takes a northerly, then a westerly course, separating the region known as Champagne Pouilleuse from the more elevated plateau of Argonne which forms the central zone of the department and stretches to the left bank of the Meuse.
Agriculture is carried on to most advantage in the Champagne and Argonne.
Dumouriez succeeded in rousing the spirit of the French; he occupied the defiles of the forest of Argonne, thus causing the enemy to lose many valuable days, and when at last they turned his position, he retreated without loss.
A flower of a rather different type, Pseudaraucaria major, exhibiting in the occurrence of two seeds in each scale an approach to the cones of Abietineae, has been described by Professor Fliche from Lower Cretaceous rocks of Argonne.
Cones of Lower Cretaceous age have been described by Fliche from Argonne, which bear a close resemblance to the female flowers of recent species of Cedrus.