Jensen, John M. Jnr.
John M. Jensen Jnr. is an independent researcher living in Florida, who has published two books on ancient civilisations and catastrophism. He has explored in depth some of the subjects touched on here. His first book was Ancient Canal Builders(a), which explores the extensive ancient canal network on the Atlantic and Gulf coasts of the United States and Mexico. His second offering is Earth Epochs(b) in which he recounts pre-historic global catastrophes, including the Younger Dryas Event of 12,900 YBP, and what he calls the Last Great Cataclysm of 5,000 YBP and the Earth Axial Tilt of 3448 YBP.
However, he seemed to go off the rails when he proposed that humans and dinosaurs co-existed and that the many thousands of dolmens found around the globe were not tombs but places of refuge from carnivorous dinosaurs. No, I’m not making this up. He deals with the subject in greater detail in the well-illustrated Earth Epochs(d). Both of his books can be downloaded for free.(a)(b)
Jensen does mention Atlantis, but without dealing with the matter in any depth, it seems to me that he does accept its reality. I do not agree with all his ideas but I think his work should be read, including his blogs(c) .