There is along the north of the Aisne a long wooded ridge, which on its northern edge slopes steeply. But the top of the ridge forms a gentle undulating slope to the south. It is not unlike the top of a rough, slightly tilted table. To a bird's-eye view this top would appear shaped rather like a very coarse-toothed comb, with the teeth jagged and broken. The top, that is to say, runs out on its south side into a succession of promontories, each ending in a round-ended bluff overlooking the Aisne valley. Some of these bluffs jut out close above the river. Others are much farther back. Between them are clefts and side valleys, in which the land slopes up from the bottom of the main valley to the top of the plateau. In the longer clefts, of course, the general gradient is much less stiff than in the shorter ones. Both the tops of the bluffs and most of the clefts are thickly wooded. The bluffs are on an average above 400 feet in height, that in fact being the general elevation of the plateau. The aspect of the edge of the corresponding plateau on the south side of the valley of the Aisne is exactly similar. Since the bluffs on the opposite sides approach each other in some places and are farther apart in others, the valley varies in breadth from half a mile to two miles. The bottom of the valley is practically flat, and through this flat tract of meadow land the river winds, now near one side of the valley, now near the other. The stream is between fifty and sixty yards wide, but, like all the rivers in this part of France, deep. Where the valley opens out there are villages and small towns. The largest place is the picturesque old city of Soissons. Now the ridge north of the Aisne extends west to east for some thirty-four miles. At Craonne, its eastern end, it rises to a summit about 500 feet high, and then falls abruptly. There is here, going from the Aisne northwards, a fairly level open gap some three miles wide. South of the Aisne, the same gap extends for about ten miles to Rheims. On each side of the gap rise hillsides clothed with woods. At the crossing of the Aisne is situated the village of Berry-au-Bac. This gap, it will be seen, forms an important feature in the Aisne battle. Above and behind the hills to the east of the gap, and across the downs, the German entrenchments extended eastward for mile after mile right away to the Argonne. It is apposite here to note that near Rheims the traverse gap widens out and passes right and left round an isolated, hilly mass, lying like an island in a stream. Up the sides of this hilly mass climb the villages of Berru and Nogent-l'Abbesse.