Complex sentence: The stratigraphic sounding beneath the Temple of Bel was conducted in 1967 by Robert du Mesnil du Buisson, who also discovered the Temple of Baal-hamon in the 1970s.
Split into simpler sentences: The stratigraphic sounding beneath the Temple of Bel was conducted by Robert du Mesnil du Buisson in 1967. The Temple of Baal-hamon was discovered by Robert du Mesnil du Buisson in the 1970s.