Eruptions along the length of the chain have created at least three major volcanic zones. The first began in the Powder Mountain Icefield 4.0 million years ago. The Mount Cayley massif began its formation during this period. Multiple eruptions from 2.2 million to 2,350 years ago created the Mount Meager massif, and eruptions 1.3 million to 9,300 years ago formed Mount Garibaldi and other volcanoes in the Garibaldi Lake area. These major volcanic zones lie in three echelon segments, referred to as the northern, central, and southern segments. Each segment contains one of the three major volcanic zones. Apart from these large volcanic zones, two large poorly studied volcanic complexes lie at the northern end of the Pacific Ranges, namely Silverthrone Caldera and Franklin Glacier Complex. They are considered to be part of the Garibaldi Volcanic Belt, but their tectonic relationships to other volcanoes in the Garibaldi chain are unclear because of minimal studies.