The angles of junction of streams adjust by erosion and sedimentation at the junction until the water surfaces and floodplains merge accordantly with each other and with the stream segment continuing downstream. A simplified geometric model of the zone of merger predicts angles of junction determined by the gradient relationships at the junction that are close to those in badland rill and gully networks. Merging streams with these predicted angles of junction should not be subject to discrete capture by each other or by their downstream continuation. Evaluation of angles of junction with regard to minimum rate of work performed by gravity produces normative equations for these angles that are unexplainedly similar to those predicted by the geometric model within the range of rates of downstream decrease of gradient typical of natural streams.