Detailed study was carried out in order to investigate flow phenomena occurring at the junction of two incoming stratified flow layers with junction angles. Various combinations of fluids with Newtonian and non-Newtonian rheological characteristics were tested in a relatively high-speed stratification where the inertia of flow cannot be neglected. The flow characteristics at the junctions were classified into six main flow modes, which were arranged in mode maps by use of generalized Reynolds numbers and viscous ratios. From the resultant mode maps it was found that a mutual relation of inertial and viscous effects is essential for the determination of flow modes in the stratified flows.