232 
THE SEINE, THE MEUSE, AND THE MOSELLE 
ing filled up the former valley-trough to a moderate depth. It 
therefore gives us au illustration of a river which has changed 
its action from degrading its slope when its volume was large to 
aggrading its slope now that its volume is small. 
\\diat the Meuse has lost the Moselle has gained, and the con- 
siderable addition that the Toul has given to its volume has 
undoubtedly confirmed its habit of swinging boldlv around the 
meanders of its lower valle}", even to the point of cutting almost 
or quite through the necks of its meander spurs. 
The Aire and the Bar . — Let us next look at tlie case of the Aire. 
Tins stream was once an affluent of the Meuse on the we.stern 
side, of its basin. but it has been diverted to swell the volume of 
tlie Seine. The elbow of cap- 
ture in this case lies about two 
miles east of Grand Pre. The 
Aire coming from the southeast 
here makes a sharp turn west- 
ward through the ridge of lower 
Cretaceous strata that bears the 
forest of Argonne and thus joins 
the Aisne. In direct continua- 
tion of the course of the Aire an 
oi)en valley leads to the Meuse a 
little below Sedan. The greater 
length of this valle}' is followed 
by a small stream — the Bar; 
but while the valley exhibits 
strong meanders of rather large 
radius, the Bar is nothing l.)ut a 
little brook that wriggles here 
and there, back and forth, on 
the valley floor. The slopes of 
the valley floor have the usual systematic arrangement — steeper 
slopes on the outside of the curves, gentler slopes on the inside. 
A s})ur that enters one of the meanders from the upland on the 
west, covered l)y the Bois la Queue near St Aignan, has so narrow 
a neck that the canal leading from the Meuse to the Seine sys-' 
tern has cut a trench through the neck instead of going around 
the spur. (See Plate V.) 
Tlie indications of the former greater volume of water in the 
stream tliat once swung boldly around tbe meanders of this 
valley are perfectly conclusive. But now the little Bar staggers 
