Final answer:
The Cascades and the Andes mountain chains are located where they are due to convergent boundaries between continental and oceanic plates.
Step-by-step explanation:
The Cascades and the Andes mountain chains are located where they are because they are formed due to convergent boundary between continental and oceanic plates. When two continental masses are moving on a collision course, they push against each other under great pressure, causing the Earth to buckle and fold. This process drags some rock deep below the surface and raises other folds, forming mountain ranges. The Alps, for example, are a result of the African plate colliding with the Eurasian plate. Similarly, the Cascades and the Andes are formed by the collision of the Juan de Fuca plate and the North American plate and the Nazca plate and the South American plate, respectively.