Why are the Appalachians lower than the the cordilleras?

The Appalachians are lower than the Cordilleras primarily due to their age and the geological processes that shaped them. The Appalachians are an older mountain range, formed around 480 million years ago, and have since experienced significant erosion and weathering, reducing their height. In contrast, the Cordilleras, such as the Rocky Mountains, are younger and still actively rising due to tectonic activity, resulting in their greater elevation. Additionally, the forces of plate tectonics that formed the Cordilleras continue to uplift them, while the Appalachians have largely settled.