Descending the ridge was the roughest piece of riding on the road to Marrakesh: the shale
gave way under the mules' feet; great rocks projected on the track.
It gets narrower and steeper as it goes on zigzagging up slabs of shale,
with only room for one camel at a time.
By the time he reached the green shale,
Enoch was trembling from muscle and nerve strain.