Hess referred to this recycling action involving mantle convection cells, upwelling mantel material, sea-floor spreading, and convergent boundaries which replasticizes old sea-floor lithosphere, as a sea-floor �conveyor belt.� Of course, this "conveyor belt" moves quite slowly by our time standards. But on a geological time scale, new MAR sea-floor is being produced at an alarming rate--as much as 2-4cm per year along Slow-Spreading Atlantic divergent zones, and as much as 10cm along Fast-Spreading Pacific divergent zones.
Exactly how oscillating polarity reversals correlate to sea-floor spreading rates over the last 4 million years is still not entirely understood. Polarity reversals would seem to have a significant impact upon mantle convection cells, which are the power source for upwelling mantle materials. At any rate, MAR fossil magnetism core samples have allowed geologists to grasp hard geological evidence in support of the plate tectonic hypothesis by plotting their paleomagnetic time scale.
Another bit of compelling evidence that supports continental drift comes from matching mountain Structural Belts across the North Atlantic to the geological time when the Appalachian mountains of North America and the Atlas mountains of northern Africa created each other through interaction between the North American and African plates.
Likewise, the same Appalachian mountain belt runs up the North American plate to disappear off the coast of Newfoundland--only to reappear again in the inter-related mountains of Ireland and Scotland, and then again on the east coast of Greenland and the west coast of Norway, which are all part of the Eurasian continental plate. All of these mountain ranges are of aproximately the same geological age and composition.
When geologists match these structural belts by reversing the effects of continental drift, the jig-saw picture that is revealed depicts the adjoining land mass of the northern African, North American and Eurasian continental plates. The single unifying factor that links them all geologically to one another is the ever-present MAR divergent boundary line.
Iceland falls on the map south-east of Greenland, but north-west of Great Britain. Its geological history presently seems unique to the Atlantic Ocean compared to the rest of the land masses discussed previously. Iceland is thought to be sitting upon what is referred to as a hot spot. The Pacific archipelago of Hawaii is the classic example of a Hot Spot/Island-Seamount Chain that stretches from Hawaii north-west to the Midway Islands, and then north to the Aleutian Trench.
