Here are many chronological iterations of the same drawing in the few weeks I have been working on it with a few altered by the computer. I work on drawings as if I am removing layers of white with my drawing implement. I set up parameters like color and textures and materials and jump in.
I never have a clear idea of the end product when I begin that way I am constantly surprised, mostly pleasantly.
Myriad Ways 
I get the same feeling of engagement , fascination and pleasure in studying these drawings of yours as I do from planting myself, nose close to a terrain, taking in the richness and complexity to be found in front of my eyes by simply studying and seeing what is there. Have you ever made ephemeral land art? There is a kinship of sensibility with these drawings of yours and land art. G
That is definitely a feeling I get as I am creating drawings like this. Like watching a landscape develop over eons and being a agent in the process. I have done some experiments with lawn mowing and compost piles that sprout potatoes and onions and squash, rock gardens and fountains . I can play with a fountain and rocks and shells for hours. Piles of tiny pebbles. If you have seen Andy Goldsworthy’s work with rocks and wood and ice. Drawing is like that for me.