Some say there are 115 elements others say 118 that we know of.
http://education.jlab.org/qa/element.htmlWhy would henges serve to illustrate a particular element?
If we combine certain henges would the result be a new element?
Is water an element anyway? Isn't it the combination of hydrogen and oxygen elements?
If we stick to the basic 'four elements' perhaps the purpose of each henge could be to inform the locals of changes within that particular elemental makeup? Some henges could be designed to give information on the sun, others on the stars in general or particular, others to do with the rotation or progression of the earth and yet others could be looking at changes in water patterns?
After the catastrophe of the ice age and whatever caused it it could be that people wanted to find a means of forecasting whether or when it was going to happen again.