macadam

a paved surface having compressed layers of broken rocks held together with tar

a type of road construction that uses layers of compacted crushed stone, bound with tar or asphalt

Macadam is a method of building roads by layering crushed stone and then binding it together with tar or asphalt. The crushed stones are packed tightly in layers to create a strong surface, and the tar or asphalt helps hold everything together, making the road more durable. This technique was developed in the 19th century and was widely used for creating smooth, stable roads, though it has since been largely replaced by more modern paving methods.