Final answer:
True, the westernmost North America formed through the uplift of the Coast Ranges and the accretion of exotic terranes during the Cenozoic era, as part of the complex geological processes.
Step-by-step explanation:
The statement that the westernmost North America was formed by the uplift of the Coast Ranges and accretion of exotic terranes during the Cenozoic is true. The geological history of the western part of the North American continent is complex and has been influenced by various factors, including plate tectonics and volcanic activity. The Coast Ranges, part of the Pacific Mountain System, indeed comprise a series of smaller mountain ranges that were largely formed during the Cenozoic era. The accretion of exotic terranes, which includes microcontinents and fragments of oceanic crust, has played a crucial role in building up the landmass as it appears today. These processes involved tectonic plates moving and colliding over millions of years, which influenced the topography we see in present-day western North America.