The fact that this 8-mile high ridge follows the equator pretty closely suggests to me that it's the remains of a fallen ring. When the ring failed some of the material would have escaped and the rest just dropped vertically onto what was then the equator. Iapetus has no atmosphere to cause the material to disperse as it fell.
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The fact that this 8-mile high ridge follows the equator pretty closely suggests to me that it's the remains of a fallen ring. When the ring failed some of the material would have escaped and the rest just dropped vertically onto what was then the equator. Iapetus has no atmosphere to cause the material to disperse as it fell.