Complex sentence: Between 1979--81 York Archaeological Trust unearthed remains of 10th-century Viking-age buildings from the Viking city of Jorvik in moist, spongy layers of earth similar to that of a peat bog.
Split into simpler sentences: Between 1979--81 York Archaeological Trust unearthed remains of 10th-century Viking-age buildings from the Viking city of Jorvik. The remains lay in moist, spongy layers of earth similar to a peat bog.