magnacycle Directory References Discover How Much Trash Is In Space? Is Cinco de Mayo Mexico's Independence Day? Poker Hands Ranked 6 Animal Species that Mate for Life 10 Greatest Baseball Players of All Time Ten Days That Vanished: The Switch to the Gregorian Calendar Why Do Some Cicadas Appear Only Every 17 Years? Contents Ask the Chatbot a Question magnacycle geology Ask the Chatbot a Question Learn about this topic in these articles:cyclothems In cyclothem…have been referred to as magnacycles. These larger units are of doubtful validity and restricted utility.Read More Britannica ChatbotChatbot answers are created from Britannica articles using AI. This is a beta feature. AI answers may contain errors. Please verify important information using Britannica articles. About Britannica AI.