A possible explanation for the origin of the Milbanke Sound Group is that it reflects a northern extension of the north-west trending subduction-related Garibaldi Volcanic Belt further south. This in turn is a segment of the Cascade Volcanic Arc in the United States, which includes Mount Baker and Mount St. Helens. However, there is currently not enough data to support this suggestion. Its origins might also result from other tectonic processes that are currently not understood.