 If this is true, then much of the rifting in the North Atlantic was likely caused by thinning and bulging of the crust as opposed to the more direct influence of the mantle plume which sustains the Iceland hotspot.In other scientific work on the path of the Iceland hotspot, no such westward track toward Canada (where the aforementioned older igneous rocks exist) can be detected, which implies that the older igneous rocks found in the Northern Atlantic may not have originated from the hotspot.Although the exact path of the Iceland hotspot is debated, a preponderance of geophysical evidence, such as the geothermal heat flux over Greenland, shows that the hotspot likely moved below Greenland around 80–50 Ma.