Hardpan or stone Screenings are much preferred for this purpose if they can be had.
"The Future of Road-making in America"
Archer Butler Hulbert
A coat of three-quarter inch stone and Screenings, of sufficient thickness to make a smooth and uniform surface, should compose the last course, and, like the other layers, should be rolled until perfectly firm and smooth.
"The Future of Road-making in America"
Archer Butler Hulbert
When the stone construction is made to the required depth or thickness, the whole surface should be subjected to a coat of Screenings about one inch thick.
"The Future of Road-making in America"
Archer Butler Hulbert