Pricing them at the level of American plates would exaggerate their value.

The rock from the islands went over top of the North American plate.

This continued as the American tectonic plates gradually moved west.

I suppose they wanted to produce more, so needed more American plates.

The North American plate went under the chain of islands.

Others may have arisen as a result of some movement of the American plate.

The islands rode over top of the North American plate.

Some of the officers were driving cars with American plates that had apparently been stolen or recovered by other federal police agents.

The island along with others was created after the breakup of the African and the American continental plates.

The North American plate was subducted under the chain of islands.