Complex sentence: He examined the rocks along a 400 miles stretch at the 49th parallel, which led him to formulate a theory of the origins of igneous rocks, and published his seminal work "Igneous Rocks and Their Origin" in 1914.
Split into simpler sentences: He examined the rocks along a 400 miles stretch at the 49th parallel, which led him to formulate a theory of the origins of igneous rocks. He published his seminal work "Igneous Rocks and Their Origin" in 1914.