The Insular Islands were a giant chain of active volcanic islands somewhere in the Pacific Ocean during the Cretaceous time that rode on top a microplate called the Insular Plate, beginning around 130 million years ago. These islands collided then fused onto the North America during the Mid-Cretaceous time. The Insular Islands were already very ancient before they collided against North America. Like the earlier Intermontane Islands, the islands were simply too massive to subduct beneath North America. The Insular Islands jammed and shut down the subduction zone. In its place, the pre-existing Farallon Trench took over as the major subduction zone.

See also

• Insular Mountains
• Omineca Arc