From A Pre-Historic Nuclear War? Reflections on Worlds Before Our Own by Brad Steiger:
"Large areas of fused green glass and vitrified cities have been found deep in the strata of archaeological digs at Pierrelatte in Gabon, Africa; the Euphrates Valley; the Sahara Desert; the Gobi Desert; Iraq; the Mojave Desert; Scotland; the Old and Middle Kingdoms of Egypt; and south-central Turkey.
In contemporary times, such material as fused green glass has only been known at nuclear testing sites (where the sand had melted to form the substance). It is quite unsettling to some to consider it possible that these sites provide evidence of a prehistoric nuclear war.
At the same time, scientists have found a number of uranium deposits that appear to have been mined or depleted in antiquity."
These areas of fused green glass have never been explained by science. They remain an enigma.
Seriously though, we have no idea what was around back then do we? Didn’t they pull up an ancient astrolabe from the med from before when the technology should have been possible?
FWIW, I watched a program on the Discovery channel (I think) in which they were trying to find the source of green glass used in some ancient Egyptian jewelry. Ultimately, they found a large deposit of it on the surface of the Sahara desert. The theory was that a meteorite detonated just above the surface of the earth - the high temps. from the explosion fused the desert sands.