You're looking for the Andes Mountains! They're the longest mountain range in the world, running along the entire western edge of South America.

Here's why the Andes fit your description:

* Snow-capped peaks: The Andes are home to numerous mountains that reach high enough to have permanent snow cover. This is especially true in the southern part of the range, where peaks like Aconcagua (the highest mountain outside of Asia) are found.

* Active volcanoes: The Andes are also a zone of intense volcanic activity. This is due to the process of subduction, where the Nazca Plate is being forced under the South American Plate. This creates a chain of volcanoes, many of which are still active. Some famous examples include Cotopaxi in Ecuador and Villarrica in Chile.

Let me know if you'd like to know more about specific peaks or volcanoes!