Complex sentence: This began to change in 1956 when the crash mapping program of Operation Stikine identified a number of Cenozoic volcanoes in northwestern British Columbia, including the Level Mountain Range, the Iskut-Unuk River Cones and the Mount Edziza volcanic complex.
Split into simpler sentences: This began to change in 1956 when the crash mapping program of Operation Stikine identified a number of Cenozoic volcanoes in northwestern British Columbia. Among these were the Level Mountain Range, the Iskut-Unuk River Cones and the Mount Edziza volcanic complex.