Wikipedia:Reference desk/Archives/Language/2022 December 3

= December 3 =

Why "coal measures"?
The coal measures is a lithostratigraphical term for the coal-bearing part of the Upper Carboniferous System.

measure lists a general sense of "act or result of measuring" and a specific sense of "(geology) A bed or stratum. [from 17th c.]", but how the one is supposed to yield the other, or how this geological usage relates to any of the other meanings of the term, escapes me. The etymonline entry doesn't mention it explicitly, and again if any of what they do develop transparently leads to it, I'm failing to follow. Any ideas?

- 2A02:560:585D:6400:DC9:F55F:2137:F440 (talk) 23:35, 3 December 2022 (UTC)
 * The Oxford English Dictionary defines this sense of "measure" as A stratum or bed of mineral. Now only in plural. For the etymology, it says it is "perhaps concr[etely] of sense 7", where sense 7 is Any of various specific units of capacity (formerly also of length). Also: the quantity of a substance represented by such a unit. with examples like "two measures of sugar", "twenty measures of wheat", etc. CodeTalker (talk) 01:42, 4 December 2022 (UTC)
 * I grew up in the Latrobe Valley in Australia, an area with massive brown coal (lignite) deposits. I can definitely recall the word "measures" used to describe "our" coal. Here is a relatively recent paper about the area that includes the word in the title. HiLo48 (talk) 01:54, 4 December 2022 (UTC)
 * Yes, we have a coal measures article, but I believe the OP was asking about the etymological relationship between the two definitions. Alansplodge (talk) 11:48, 4 December 2022 (UTC)
 * In this article from 1805 the term is used in singular form, accompanied by the puzzling adjectives heaving and shuttle. The term measure can be used for an unspecified amount, as in a good measure of cloth. If I can believe Wiktionary, its Latin etymon mensura could also be used figuratively for an (unspecified) amount. The transfer of this sense to a stratum could do with a further explanation, though. --Lambiam 16:00, 4 December 2022 (UTC)
 * The earliest use of the sense of a mineral layer I saw is from 1686. Sometimes the earliest uses give a hint of an unexpected sense development; the only vague clue is that the text explains that the thicker measures or floors are partitioned by thin partings or lamings, so the term measure may indicate a certain substantiality of the layer.
 * Nice work. I now tried googling the likes of "heaving measure", hoping that the combined phrase constitutes a filter of sorts for the context of concern. The best result was "On the Geology of Coalbrook Dale", which contains some of the same material as your first article, but comes with a glossary, defining "heaving" as "a clay which absorbs moisture and swells by exposure to the atmosphere" and "measure" as "a term applied to all the workable strata, more particularly to the ironstone strata". While this does not directly address my original question, I'm gleaning some stuff that indirectly may.
 * For one thing, it sounds to me like "measure" was incorporated into something like mining jargon at some point, evolved the sense in question there, and then got reincorporated into mainstream use in particular phrases like "coal measures". With that background, it's only to be expected that it diverges quite a lot from any of the other senses, as well as that there's a certain opacity to that divergence.
 * For another thing, I get the feeling that a shift of perspective may be what's needed here. Instead of thinking of a coal deposit as something that has a volume, I suppose one can think of it as something that simply has a thickness. For surface dwellers like me, this becomes more natural when imagining a core sample instead of the whole thing - but for miners, it may just be the more natural way to think all along. From there, the thought process from "layer of coal" to "thickness of coal" to "measure of coal" seems almost straightforward.
 * - (OP) 2A02:560:585D:6400:C06F:7B1E:E37D:2916 (talk) 18:44, 4 December 2022 (UTC)