Complex sentence: During the early Mesolithic (Middle Stone Age, late to mid 8th millennium BC) the landscape was largely pine woodland and the valley bottom area of central Berkhamsted was probably grass-sedge fen.
Split into simpler sentences: During the early Mesolithic (Middle Stone Age, late to mid 8th millennium BC) the landscape was largely pine woodland. The valley bottom area of central Berkhamsted was probably grass-sedge fen.