pyroclastic 的词源

在地质学中，“由火山作用形成”，特别是指在火山喷发中快速移动、密集的超热灰烬、气体和岩石浪潮；到1862年开始指代由此产生的岩石；参见 pyro- 意为“火” + clastic，表示“破碎成片，碎片”。

The word "ash" is not a very good one to include all the mechanical accompaniments of a subaerial or subaqueous eruption, since ash seems to be restricted to a fine powder, the residuum of combustion. A word is wanting to express all such accompaniments, no matter what their size and condition may be, when they are accumulated in such mass as to form beds of "rock." We might call them perhaps "pyroclastic materials," but I have endeavoured in vain to think of an English word which should express this meaning, and believe, therefore, that the only plan will be to retain the word "ash," giving it an enlarged technical meaning, so as to include all the fragments accumulated during an igneous eruption, no matter what size or what shape they may be. [J. Beete Jukes, "The Student's Manual of Geology," Edinburgh, 1862]

“灰烬”这个词并不太适合用来包含所有地面或水下喷发的机械伴随物，因为灰烬似乎仅限于细粉状物质，即燃烧的残余。我们需要一个词来表达所有这些伴随物，无论它们的大小和状态如何，当它们积累成足以形成“岩石”的床层时。我们或许可以称它们为“火山碎屑材料”，但我努力想找一个英语词汇来表达这个意思，却始终没有成功。因此，我认为唯一的办法就是保留“灰烬”这个词，赋予它更广泛的技术含义，以包括在火山喷发中积累的所有碎片，无论它们的大小或形状如何。[J. Beete Jukes，《学生地质学手册》，爱丁堡，1862年]