The grey stretch of road has a layer of RAP (Reclaimed Asphalt Paving) laid on it.This short stretch of road had a top layer of black/grey gravel, unlike the normal sandy colour of the rest of the road.
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Wonder when/if this rock rolled down the mountain??
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Approaching the bottom of the valley.
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Rode some nice fast, flat gravel and after a while, found a shady spot next to the road to have some snacks and a drink
It's the stuff removed when the highway surface is repaired/replaced.