the Kootenai River (US spelling). For convenience the Rocky Mountain Trench may be divided into two sections, the Northern Trench (between the Muskwa Ranges and Interior Mountains) and the Southern Trench (between the Continental Ranges and Columbia Mountains), separated by the northeastern portion of the Interior Plateau west of the Hart Ranges. The Copley Range of the Arctic Pacific Lakes Provincial Park forms the drainage divide between the northerly Parsnip-Finlay-Peace system into the Arctic Ocean (via the Mackenzie River) and the southwesterly McGregor-Fraser system into the Pacific Ocean. The northern end of the Columbia Mountains at ~54°N near Prince George, British Columbia, where the Fraser River leaves the Trench to enter the Interior Plateau, may be used for this purpose. The northern portion of the Trench is dominated by strike-slip faulting, while the southern part of the Trench was created by normal faults. Despite differences in timing and faulting styles of the northern and southern portions, they were aligned with each other because faulting for both was controlled by a pre-existing, west-facing, deep basement ramp with over of vertical offset. Northern Rocky Mountain Trench The Northern Rocky Mountain Trench is closely aligned with the Tintina Trench near the British Columbia-Yukon border at 60 degrees north latitude, and the two trenches could arguably be classified as one and the same - or 'extensions' of each other. The Tintina Trench extends further north-westward through the Yukon into Alaska. The visible expression of the two trenches is lost where they plunge under the boreal forests of the Liard Plain proximate to the small communities of Watson Lake, Yukon and Lower Post, BC. The highest point in the northern Trench is Sifton Pass at an elevation of about near the bend of Scarcity Creek. Geology Right-lateral strike-slip movement of the Tintina Fault on the Tintina-Northern Rocky Mountain Trench may have begun during the middle Jurassic. The fastest rates of slip probably occurred during two pulses in the middle Cretaceous and early Cenozoic, respectively, with the latter probably occurring during the Eocene. Between to over of total right-lateral movement has occurred, of which of offset has occurred since the mid-Cretaceous. The result is that terrains to the west of the fault system have moved toward the north. In the context of plate tectonics, strike-slip movement of the Tintina Fault on the Tintina-Northern Rocky Mountain Trench is also related to strike-slip movement along the San Andreas