I came across this article today (“Megalithic Quarrying Techniques and Limestone Technology in Eastern Spain“) and thought I’d share it with readers. I get lots of questions about the “impossibility” of quarrying huge stones for megalithic structures, usually with respect to Egypt. This article deals with even older cultures and goes into a nice level of detail about the use of fire for quarrying.  From the abstract:

Evidence in Eastern Spain and in the Balearic Islands indicates that during the building period of the megaliths and thereafter the inhabitants of this region developed a considerable limestone technology. This technology embraced an empirical knowledge of carbonate chemistry and karst geology which enabled them to quarry large limestone blocks to gain a maximum of usable material with a minimum of effort. It appears that one of the quarrying methods used was based on the chemical dissociation by fire of standing stone blocks at their attachment points, a technique hitherto unknown or unreported in the literature.

Pretty cool. Once again, aliens need not apply.