Complex sentence: The next excavation attempt, made in 1861 by a new company called the Oak Island Association, resulted in the collapse of the bottom of the shaft into either a natural cavern or booby trap underneath.
Split into simpler sentences: The next excavation attempt was carried out in 1861, by a new company called the "Oak Island Association". Sometime during excavating the bottom of the shaft that had been dug out over the years collapsed into either a natural cavern or a booby trap underneath.