Talk:Dynamic topography
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The same thing twice?
[edit]I can believe that large-scale stuff from the mantle is like ocean dynamic topography. But I have a hard time believing that the mid-ocean ridges are. They are too spiky. Aren't they more like waves? William M. Connolley (talk) 18:28, 8 May 2010 (UTC)
- Standing waves? Isn't the "spikiness" just due to brittle failure over the underlying broad swell of this long-term standing wave? Note, I really just stumbled on this from talk "eavesdropping", interesting... Vsmith (talk) 11:48, 9 May 2010 (UTC)
- Yes, Vsmith is right: spikiness is the lithosphere. The broad swell is due to upwelling of hot material in the mantle underneath them that creates a upward-directed normal traction at their base.
- The lithosphere acts as a filter: because of its flexural rigidity, it flexes at wavelengths of 50–100 km. Any deeper-derived signals smaller than that get smoothed out, and topography smaller than that has a great amount of support derived from flexure (instead of standard buoyancy-derived isostasy. Awickert (talk) 16:19, 9 May 2010 (UTC)