Original sentence: The Beaver River is a tributary of the Liard River, entering that stream in the area of its Grand Canyon just south of the British Columbia-Yukon border (the 60th Parallel.after running generally south-east from its origin in the extreme southeast corner of the Yukon Territory
Edited sentence: The Beaver River is a tributary of the Liard River, entering that stream in the area of its Grand Canyon just south of the British Columbia-Yukon border (the 60th Parallel)  after running generally south-east from its origin in the extreme southeast corner of the Yukon Territory