James Grey Jackson, An account of the empire of Marocco… (1811)
“ If it continues, the most numerous caravans are often buried under mountains of sand, which, like the tempestuous billows in a storm, advance in an undulating manner, stopping and accumulating wherever they find the smallest substance to impede their progress, insomuch that in a few hours a mountain of sand is thus accumulated, where it was before an uninterrupted plain, then the wind shifting, scatters in the air these newly constructed mountains, forming amidst this chaos dreadful gulphs and yawning abysses ”
