Pliosaur Posted April 30, 2014 Share Posted April 30, 2014 Hi, Everyone Does anyone know why the magnetic reversal supports the theory of plate tectonics? Gabriel Link to comment Share on other sites More sharing options...
Auspex Posted April 30, 2014 Share Posted April 30, 2014 I don't think it does, directly. It is evidence of the fluid nature of the core, which is required by the tectonic model, though. 2 "There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant “Try to learn something about everything and everything about something.” - Thomas Henry Huxley >Paleontology is an evolving science. >May your wonders never cease! Link to comment Share on other sites More sharing options...
painshill Posted April 30, 2014 Share Posted April 30, 2014 It does provide some support. The original geologic evidence for past magnetic reversals came in part from the observation that the ocean floor has anomalous magnetic “stripes”. They can be detected by magnetometer readings in certain areas where the sea floor is no older than about 180 million years since that’s about the age beyond which there are no intact floors which have not been subducted (one plate sliding beneath another and ultimately sinking into the mantle). These features were presumed to be connected to ocean floor “thrust-spreading”, for which plate tectonics provided a convincing explanation. That’s how we know the continents were all originally joined together in the form of a giant chicken called “Betty”: (sorry… I may not have that last bit completely correct) 3 Roger I keep six honest serving-men (they taught me all I knew);Their names are What and Why and When and How and Where and Who [Rudyard Kipling] Link to comment Share on other sites More sharing options...
fossilized6s Posted April 30, 2014 Share Posted April 30, 2014 Wow......Betty......i guess the chicken did come first!! Lol ~Charlie~ "There are those that look at things the way they are, and ask why.....i dream of things that never were, and ask why not?" ~RFK ->Get your Mosasaur print ->How to spot a fake Trilobite ->How to identify a CONCRETION from a DINOSAUR EGG Link to comment Share on other sites More sharing options...
Auspex Posted April 30, 2014 Share Posted April 30, 2014 It just occurred to me that I had overlooked somehow the the most important connection between polarity reversals and proof of seafloor spreading, but painshill has saved the day. "There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant “Try to learn something about everything and everything about something.” - Thomas Henry Huxley >Paleontology is an evolving science. >May your wonders never cease! Link to comment Share on other sites More sharing options...
Missourian Posted April 30, 2014 Share Posted April 30, 2014 The mirrored arrangement of the magnetic stripes on opposite sides of the ridges was one of the clinchers: Context is critical. Link to comment Share on other sites More sharing options...
Mediospirifer Posted May 1, 2014 Share Posted May 1, 2014 There's also the study of what's called "Apparent Polar Wander". Researchers look at the magnetic orientations within rocks of the same age in different locations within a continent, and triangulate the location of the magnetic North Pole relative to the rocks when they were formed. By comparing magnetic North measurements from different continents, they can try to tease out how much of the variation is actual polar wander, and how much is continental drift. It's an interesting field, and i don't know a lot about it beyond the Wiki page. I learned about it after my husband and I found some odd rocks here in Ithaca. He went online looking up information about intrusive dikes in Tompkins County, and found that what we had seen was a Jurassic-age kimberlite dike, which has been studied extensively in apparent polar wander studies. That was a new one for us! 2 Link to comment Share on other sites More sharing options...
ashcraft Posted May 1, 2014 Share Posted May 1, 2014 They also explain the New Madrid fault. Back in the olden days of my youth, there was no good explanation of why the New Madrid fault was so active, since it is in the middle of a continental plate. Research discovered a series of anomolous magnetic lines trending from the northeast to southwest, they named it the Commerece Linement. They were formed when the North American plate tried to pull apart, allowing magma to rise up in the split, and freezing in place, locking the iron atoms into a different magnetic orientation then the rest of the rock. This led to the discovery of the Reelfoot Rift, a weak spot in the North American plate, of which the New Madrid fault is a part of. fkaa 1 ashcraft, brent allen Link to comment Share on other sites More sharing options...
Bev Posted May 5, 2014 Share Posted May 5, 2014 Fascinating topic! Thank you all for sharing! The more I learn, I realize the less I know. BluffCountryFossils.NET Fossil Adventure Blog Go to my Gallery for images of Fossil Jewelry, Sculpture & Crafts Pinned Posts: Beginner's Guide to Fossil Hunting * Geologic Formation Maps Link to comment Share on other sites More sharing options...
Recommended Posts