I recently read that Joseph Smith said the City of Enoch was located where the Gulf of Mexico is today. When God translated the entire city, the gulf was created. Interesting idea, so I read up on it and the geology of that area.
March 30, 1873: At evening prayer circle: President Young said Joseph the Prophet told me that the Garden  of Eden was in Jackson County, Missouri, and when Adam was driven out of the Garden of Eden, he went about 40 miles to the place which he named Adam ondi Ahman, and there built an alter of stone and offered sacrifice. That altar remains to this day. I saw it as Adam left it, as did many others, and through all the revolutions of the world, that alter had not been disturbed. Joseph also said that when the City of Enoch fled and was translated, it was where the gulf of Mexico now is; it left that gulf a body of water. (Wilford Woodruff Journal)
After reading this, I recalled that in the book, Visions of Glory, Spencer had talked about the Gulf of Mexico as well. He saw that a landmass rose up from the gulf:
Gulf of Mexico. Almost all of California was in ruin, with less destruction further away from the coast. I saw that a great landmass had risen up into the Gulf. It extended from Mexico to Florida and consisted of a few large islands that replaced the water of the gulf. I did not think to look toward Cuba. In some places, the new land met Mexico, Texas, and Florida, but there was also a large waterway separating most of the new land from America. I did not see where the land came from. It either rose up from the Gulf floor, or was pushed north by the earthquakes from South America. The land was not barren all over, but large parts of it had trees and other vegetation. Some parts of it were just muddy islands. I am at a loss to explain where it came from. This great landmass created a tidal wave that did a great deal of devastation as far north as Chicago. About two-thirds of the Gulf was now a series of large islands. I did not see the damage this caused worldwide, but I can only assume it was extensive. (Pontius, John. Visions of Glory: One Man’s Astonishing Account of the Last Days (p. 118). Cedar Fort, Inc.. Kindle Edition.)
Later in the book, Spencer identifies this region as where the City of Enoch will return:
I am not sure how many years had passed by this time. It was still pre-Second Coming. In my visions of these times, I was not shown the return of the City of Enoch. I just knew that they were among us and working on the same labors as we were. The City of Enoch now occupied some, or most, of the new landmass in the gulf. The details of their return and the particulars of their mission were not revealed to me. (Pontius, John. Visions of Glory: One Man’s Astonishing Account of the Last Days (p. 221). Cedar Fort, Inc.. Kindle Edition.)
Today, about half of the basin of the Gulf of Mexico basin is shallow continental shelf waters. The bottom of the gulf is made up of sedimentary rocks and the entire gulf is approximately 930 miles wide.
Geologists believe that the gulf was formed by plate tectonics, when the Pangea rifted. “Before the Late Triassic, the area now occupied by the Gulf of Mexico consisted of dry land, which included continental crust that now underlies Yucatán, within the middle of the large supercontinent of Pangea.”