After I had made the main article last time, I found another illustration showing concentrations of seamounts, underwater montains which are thought by some to indicate sunken land areas. This is really one of Menard’s illustrations done over but I thought it was reproducing. It is from a standard reference book on Oceanography and Oceanic Geology and the copy I found was opn a website discussing the Mid-Ocean ridges.
Best Wishes, Dale D.