Page "Mindanao" Paragraph 9

The mountains of Mindanao can be conveniently grouped into ten ranges, including both complex structural mountains and volcanoes.

The structural mountains on the extreme eastern and western portions of the island show broad exposures of Mesozoic rock with ultrabasic rocks at the surface in many places along the east coast.

Other parts of the island consists mainly of Cenozoic and Quaternary volcanic or sedimentary rocks.