The Siwash Rock is a monolithic one. It is located just off the northwest coast of Stanley Park and rises up to 18 meters high. The rock is considered a natural landmark of the city.
The rock is of volcanic origin and was formed around 32 million years ago. Magma rose to the surface through a fissure in the earth's crust and formed a basalt column in the middle of the sedimentary rock that now forms the park's floor. This was more resilient than the surrounding sandstone rocks, which were worn away by erosion over time. Siwash Rock is the only rock of its kind in the Vancouver region