The western part of the Geoscience Garden represents the Cordilleran mountain belt, where the crust has been squeezed and heated by tectonic movements between the North American and Pacific plates. Layers have been folded, and new minerals have given the rocks a strong 'grain' or fabric. In the far west, molten rock from below has produced lava from volcanic eruptions.
The rocks in this area include:
- Slate, metasandstone, metaconglomerate: rocks that were originally sedimentary but have been metamorphosed; the original layers are still visible but a new fabric has developed due to tectonic squeezing.
- Gneiss and amphibolite: New minerals have grown while the rock was heated and squeezed, so that the original rock type is no longer evident.
- Pumice: Lava that became frothy while it was erupted, and cooled rapidly to form porous, glassy lava.