In order to create value in his drawing head of a satyr, michelangelo used both hatching and a variation where the lines overlap, allowing for the depiction of darker tones.

Crosshatching

Michelangelo used both hatching and cross-hatching in his drawing head of a satyr to create value.

Hatching is an artistic technique that creates tonal or shading effects by drawing closely spaced parallel lines.

Crosshatching is an extension of hatching, it also uses fine parallel lines which are drawn closely together to create the illusion of a mesh-like pattern.