With this exercise marks will be used to create surface textures, based on pictures. I decided to work with these 2 pictures. The first one is from the old mills area in Minneapolis:
The whole picture would be a bit too much :-). With a viewing frame I picked out this square to work with:
The other picture is from a pile of wood blocks:
Again using the viewing frame I selected a smaller area:
Next step is to use marks to create an equivalent of the picture on paper, focussing on the surface texture of the picture. And this is what I made. Mind you drawing is not my strongest side <gr>.
In this drawing of the mills area I used pencil: