Complex sentence: The craton is named after the Laurentian Shield, which in turn is named after the Laurentian Mountains, which were named after the Saint Lawrence River which in turn was named after Lawrence of Rome.
Split into simpler sentences: The craton is named after the Laurentian Shield, which in turn is named after the Laurentian Mountains. The mountains received their name from the Saint Lawrence River, which was named after Lawrence of Rome.