Complex sentence: He and his two sons systematically investigated every stratum of rock to locate the source of the block they had found the previous summerl they eventually identified the productive layers, including the Phyllopod bed, in what would become the Walcott Quarry.
Split into simpler sentences: He and his two sons systematically investigated every stratum of rock to locate the source of the block they had found the previous summer. They eventually identified the productive layers, including the Phyllopod bed, in what would become the Walcott Quarry.