Complex sentence: Consequently, the region became blanketed with exposed rocky outcrops permanently stained charcoal black, first by the air pollution from the roasting yards then by the acid rain in a layer which penetrates up to three inches into the once pink-grey granite.
Split into simpler sentences: Consequently, the terrain was made up of exposed rocky outcrops permanently stained charcoal black, first by the air pollution from the roasting yards. Acid rain added more staining, in a layer that penetrates up to three inches into the once pink-grey granite.