Volcanic activity of the final Shovelnose stage involved the eruption of two lava domes at the east and southeast margins of the Mount Cayley massif in the upper Shovelnose Creek valley. The southeast dacite dome forms high cliffs of small diameter columnar joints. It was the source of a long dacite flow that extends down the Shovelnose and Turbid creek valleys to near the Squamish River. The east lava dome was built upon blocky bedded tephra overlying basement rocks and consists of a steep-sided columnar jointed mass of dacite.