Dont want to drift too far off topic on this, hence the tentative ley connection. Cant really subscribe to the theory too much myself - but its a 'thort'!

W

Consider the cup as a receptacle for quartz fragments, dark ancient evening, no light pollution - shaman pounding the whole lot with a pestle (cant remember which is which!) - palaeolithic pyrotechnics perhaps?
(excuse the inadvertant alliteration!)
W