Complex sentence: Even so, there must have been an eruption around this time, since in 1880, Verbeek investigated a fresh unweathered lava flow at the northern coast of Perboewatan, which could not have been more than a couple of centuries old.
Split into simpler sentences: Even so, there must have been an eruption around this time. In 1880, Verbeek investigated a fresh unweathered lava flow at the northern coast of Perboewatan, which could not have been more than a couple of centuries old.