Last Updated: Oct 23, 2016 Views: 21
I had difficulty answering this question because none of the published accounts I could find of the slab thought it relevant to include info about the pipes, since they are modern. But I asked Dr. Brill, who investigated the slab's composition in the 1960s, about them and he said they were installed between 1955-1959 to hold electrical lines when the "cave" was converted to a museum exhibition space and required additional lighting. He said the pipes were exposed when the team investigating the slab was given permission to dig around it to extract a core sample, but that they had only recently (last decade) been installed to hold the electrical wires.
Dr. Brill was surprised that wasn't mentioned in the published accounts of the slab, so I will have to go back and see if I overlooked something! Great question!! Never thought about what they were, but when I did, I assumed they were older and related to drainage of the site, somehow. So thanks for an interesting investigation. Let me know if you have other questions.