Dr. C. Callaway — On River Curves. 451 



Berkeley and Tewkesbury was directed obliquely up the valley, 

 a discovery which furnished the key to the relative ages of the 

 Severn and the Thames. 



Mr. S. S. Buckman also has worked with success in the same field, 

 his ingenious paper in the Geological Magazine^ for August being 

 only one of several contributions on river development. Some 

 important observations on the curves of rivers have also been made 

 by Dr. Ellis.- He remarks that all the affluents on both sides of the 

 Severn in the Gloucester area come in on the convex side of the 

 curves, and he notices that in all the windings of the Wye known 

 to him, "where the river describes a great curve round a plain, one 

 or more tributaries flow in at the convexity." Dr. Ellis considers 

 that this effect is due to the tendency of the tributaries " to break 

 away their banks on the lower side, at their confluence with the 

 main stream, and to join together." This explanation I am unable 

 to accept ; but Dr. Ellis has hit upon a truth, and it has suggested 

 to me the investigation of an interesting problem. 



I have examined large numbers of Ordnance maps on the one-inch 

 scale. They are from Western England, North, South, and Central 

 Wales, the Lake District, the Highlands of Scotland, and many parts 

 of Ix-eland. The result of this inquiry was the induction that in the 

 vast majority of cases, probably nine out of ten, the affluents of the 

 rivers enter on the convex side of the curves. This was true, not 

 only of the main streams, but of the tributaries of the tributaries. 

 I will give a few examples. The Severn between Shrewsbury and 

 its junction with the Fyrnwy is about twelve miles in length as 

 the crow flies, but probably nearly thirty miles in its actual course. 

 Nineteen affluents are indicated on the one-inch map. Of these 

 fifteen come in on the convex, two just above the convex, and two 

 on the straight, but these are just opposite each other. Shrewsbury 

 and Ironbridge ai'e about thirteen miles from each other. The river 

 makes numerous bends, generally in alluvium. Ten tributaries 

 enter on the convex, two just above the convex, three on the con- 

 cave, and two opposite each other, one on the convex, the other 

 on the concave. Take the river Lug for a dozen miles below 

 Leominster. About eight affluents enter on the convex, one comes 

 in on the concave, and two enter opposite to each other, the larger 

 stream on the convex side. Between Monmouth and Eoss, a distance 

 of nine miles as the crow flies, there are about a dozen flexures, with 

 ten tributaries entering on the convex or just above it, and two on 

 the concave, the concavities in the last two cases being subordinate 

 to large convexities. The number of curves between Ross and 

 Hereford (11 miles) is also very numerous, and all the fifteen 

 affluents come in on the convex, or a little above it. 



Turning to foreign countries, we discover the operation of the 

 same law. For example, most of the tributaries of the Missouri 

 enter on the convex side of the curves. Taking: them from north to 

 south, we notice that the rule is followed by the Big Sioux, the 

 Kansas, the Mississippi, the Ohio, and many others, while I can find 

 1 p. 366. 2 Loc, cjt. 



