Complex sentence: At Herbertson's recommendation, in 1913 Crawford joined William Scoresby Routledge and Katherine Routledge's expedition to Easter Island as an assistant; the expedition was put on with the intent of learning more about the island's first inhabitants and its Moai statues.
Split into simpler sentences: At Herbertson's recommendation, in 1913 Crawford gained employment as an assistant on William Scoresby Routledge and Katherine Routledge's expedition to Easter Island. The expedition had the intention of learning more about the island's first inhabitants and its Moai statues.