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On About.com, I saw the Dââ refered to as the "Bullen Layer". I've seen "Bullen Discontinuity" used for the Dâ as well. However, the orignal Bullen Discontinuity article here described the term as if it were the Lehmann discontinuity (in between outer & inner core). So, which is which? I find myself confused right now. Iotha 02:58, 3 November 2005 (UTC)
Googling for "Bullen discontinuity" (in quotes) today returns 1,020 hits, whereas "Inner core boundary" returns 155,000 hits. Since Wikipedia has articles on all the other major boundaries but not on this one, I suggest one be created under the name "Inner Core Boundary" and that "Bullen discontinuity" redirect to it. Vaughan Pratt ( talk) 19:47, 14 May 2014 (UTC)
when the core grows to the surface?If it increases each year by 1cm its going to happen. âPreceding unsigned comment added by MidNiteNeko ( talk ⢠contribs) 13:38, 6 October 2007 (UTC)
The phrase "The top of Dââ has been observed in some regions to be marked by a seismic velocity discontinuity (sometimes known as the Gutenberg discontinuity)" is contradicted by a 2001 article: http://www.geotimes.org/jan01/earthsinterior.html. Here, the Dââ layer is NOT part of the CMB but it is rather on top of it. See the last picture to get a visual idea. George Rodney Maruri Game ( talk) 03:54, 26 January 2011 (UTC)
Therefore in the sentence it should be changed to "The bottom of D" has been observed ......" which would make it correct. â Preceding unsigned comment added by Martin Hind ( talk ⢠contribs) 13:25, 8 March 2011 (UTC)
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There is a section currently on the Gutenberg discontinuity being at about 2900 km depth. The Gutenberg discontinuity within geosciences often also refers to a boundary at the lithosphere-Asthenosphere boundary, not near the CMB (see [1]). It is difficult to find a primary source on the name "Gutenberg Discontinuity" referring to the CMB. A google scholar search on "core gutenberg discontinuity" yields papers from the early 1900's. In fact, this paper ( https://pubs.geoscienceworld.org/ssa/bssa/article/54/5A/1299/116273/the-fine-structure-of-the-earth-s-core) affirms that Gutenberg discovered a discontinuity but never refers to it as the "Gutenberg discontinuity" Scootalmighty ( talk) 15:16, 3 July 2018 (UTC)
A agree that the Gutenberg discontinuity section leads to confusion because in modern times the 'G' typically refers to a decrease of seismic velocity with depth at around ~100 km. Gutenberg may have discovered the seismic discontinuity associated with the core-mantle boundary, but currently in the field it is never referred to as the Gutenberg discontinuity. It would be interesting to add a section detailing the history of the nomenclature, though. Njmancinelli ( talk) 17:37, 4 August 2018 (UTC)
References
Core mantle boundary 103.240.163.12 ( talk) 07:16, 21 June 2022 (UTC)