Here's some interesting quotes to put things in perspective on Mormonism's teachings about the history of western Missouri. If anyone uses these for their Geology, Anthropology, or Archaeology PhD Dissertations then I'd like to know ;)
http://emp.byui.edu/marrottr/327Folder/Garden%20of%20Eden%20Jackson%20Co.htmlBruce R. McConkie, Mormon Doctrine, p. 20. ADAM-ONDI-AHMAN. The early brethren of this dispensation taught that the Garden of Eden was located in what is known to us as the land of Zion, an area for which Jackson County, Missouri, is the center place. In our popular Latter-day Saint hymn which begins, "Glorious things are sung of Zion, Enoch's city seen of old," we find William W. Phelps preserving the doctrine that "In Adam ondi-Ahman, Zion rose where Eden was." And in another hymn, written by the same author in the days of the Prophet Joseph Smith, we find these expressions;
Orson F. Whitney, Saturday Night Thoughts, p. 38. The Old-New World.--America, according to Joseph Smith, is the Old World--not the New.1 The primeval Garden was in that part of Missouri now called Jackson County. Our First Parents, after their expulsion from Eden, dwelt in the place where stood this altar. The Lord named it Adam-ondi-Ahman, "because it is the place where Adam shall come to visit his people, or the Ancient of Days shall sit, as spoken of by Daniel the Prophet."2
John A. Widtsoe, Evidences and Reconciliations, p.396-97
In conversation with Orson Hyde, on March 15, 1857, President Young said:
You have been both to Jerusalem and Zion, and seen both. I have not seen either, for I have never been in Jackson County. Now it is a pleasant thing to think of and to know where the Garden of Eden was. Did you ever think of it? I do not think many do, for in Jackson County was the Garden of Eden. Joseph has declared this, and I am as much bound to believe that as to believe that Joseph was a prophet of God. (Journal History, March 15, 1857)
That is the position of the Latter-day Saints today, with respect to the much-discussed location of the Garden of Eden.
Adam, after his expulsion from the Garden of Eden, lived in the vicinity of the great Missouri and Mississippi rivers. As his descendants multiplied, they would naturally settle along the fertile and climatically acceptable river valleys. When the flood came in the days of Noah, the Mississippi drainage must have increased to a tremendous volume, quite in harmony with the Biblical account. Noah's ark would be floated on the mighty, rushing waters, towards the Gulf of Mexico. With favorable winds, it would cross the Atlantic to the Eastern continents. There the human race, in its second start on earth, began to multiply and fill the earth.
The location of the Garden of Eden in America, and at Independence, Missouri, clears up many a problem which the Bible account of Eden and its garden has left in the minds of students.
Encyclopedia of Mormonism, Vol.1, ADAM-ONDI AHMAN. The Prophet's revelations indicated several things about the area: (1) the Garden of Eden was located in Jackson County, Missouri, and after Adam was expelled from the garden, he went north to Adam-ondi-Ahman; (2) three years before Adam's death, he gathered the righteous of his posterity to Adam-ondi-Ahman and bestowed upon them his last blessing; (3) this site would be the location of a future meeting of the Lord with Adam and the Saints, as spoken of by the prophet Daniel (Dan. 7:9-14, 21-27; 12:1-3).
Encyclopedia of Mormonism, Vol.2, GARDEN OF EDEN. Neither biblical records nor secular history and archaeological research identify the dimensions or the location of the garden in terms of the present-day surface of the earth. Latter-day revelation specifies that as a mortal, Adam lived at Adam-ondi-Ahman in what is now Daviess County, Missouri (D&C 107:53-56; 116:1; 117:8). Several early LDS leaders, among them Brigham Young and Heber C. Kimball, stated that the Prophet Joseph Smith taught them that the Garden of Eden was located in what is now Jackson County, Missouri (JD 10:235; cf. 11:336-7; DS 3:74).
Encyclopedia of Mormonism, Vol.2, INDEPENDENCE, MISSOURI. Anxious to know exactly where the promised city would be and when it would be built, the Saints were excited when in 1831 a series of revelations identified Missouri as the general location of the city of Zion, that "Independence is the center place, and a spot for the temple is lying westward, upon a lot which is not far from the courthouse" (D&C 57:1-3; 45:64-66; 48:4-6; 52:1-5, 42-43). Subsequently, Joseph Smith also indicated that the Jackson County area had been the location of the Garden of Eden.
Milton R. Hunter, Pearl of Great Price Commentary, p. 108. As a result of modern revelation, Latter-day Saints believe that the Garden of Eden was located in America, in the present state of Missouri.3 In the Scrapbook of Mormon Literature, the following statement is made: "In 1832 Joseph Smith made the startling declaration that the Garden of Eden had its existence on the American continent, even in Jackson County, Missouri."4 President Brigham Young declared:
In the beginning, after this earth was prepared for man, the Lord commenced His work upon what is now called the American continent, where the Garden of Eden was made. In the days of Noah, in the days of the floating ark, He took the people to another part of the earth; the earth was divided, and there He set up His kingdom.5
In March, 1832, the Lord made His first mention in latter days of "Adam-ondi-Ahman."6 Six years later (July, 1838), He pointed out to the Prophet that Adam-ondi-Ahman was "the land where Adam dwelt."7 The previous month the Prophet and some of the other church leaders were looking around for a place to establish a Latter-day Saint settlement. They selected a beautiful site which they named Spring Hill, Missouri.8 Even before this time (March 28, 1835) God told the Prophet Joseph Smith that three years prior to Adam's death the Ancient of Days called all of his righteous posterity together "into the valley of Adam-ondi-Ahman, and there bestowed upon them his last blessing."9
Journal of Discourses, Vol.10, p.235, Heber C. Kimball, June 27, 1863. We have been taught that our Father and God, from whom we sprang, called and appointed his servants to go and organize an earth, and, among the rest, he said to Adam, "You go along also and help all you can; you are going to inhabit it when it is organized, therefore go and assist in the good work." It reads in the Scriptures that the Lord did it, but the true rendering is, that the Almighty sent Jehovah and Michael to do the work. They were also instructed to plant every kind of vegetable, likewise the forest and the fruit trees, and they actually brought from heaven every variety of fruit, of the seeds of vegetables, the seeds of flowers, and planted them in this earth on which we dwell. And I will say more, the spot chosen for the garden of Eden was Jackson County, in the State of Missouri, where Independence now stands; it was occupied in the morn of creation by Adam and his associates who came with him for the express purpose of peopling this earth.
Journal of Discourses, Vol.17, p.188, Orson Pratt, October 11, 1874. Where was that valley in which that grand patriarchal gathering was held? It was about fifty, sixty or seventy miles north of Jackson County, Missouri, where the Zion of the latter days will be built. Where the garden of Eden was is not fully revealed; where Adam eat the forbidden fruit is not revealed so far as I know, that is, the particular location on the earth, no revelation informs us where he passed the first few centuries of his life; but suffice it to say that, when Adam was about six or seven hundred years old there was a great gathering of the people. Enoch, the seventh from Adam, who lived contemporary with his old ancestor, and others who were called by him, went forth and gathered out the righteous from all the nations, and as there was not Atlantic Ocean in those days rolling between the eastern and western continents, they could gather together by land from Asia, Africa and Europe. In those days the earth was not divided as it was after the flood, in the days of Peleg. In that gathering many came from the ends of the earth. Adam might have been among the emigrating companies, if not, then, he most probably had his residence at the central place of gathering. Let this be as it may, it is not revealed. There is a place, however where this great Conference took place in ancient times, where the Lord revealed himself to the vast assembly, and stood in their midst, and instructed them with his own mouth, and they saw his face. There is the place where it was ordained that Adam should have the power, as the Ancient of Days, after a certain period and dispensations had rolled away, to come in his glory accompanied by the ancient Saints, the generations that should live after him and should take up their abode upon that land where they received their last blessing, there in the valley of Adam-ondi-ahman.
Alvin R. Dyer, Conference Report, October 1968, p. 109.f. In the course of time from the creation, in the days of Peleg, or about the year 2200 B.C., Just prior to the confusion of the languages, the single continent of land that had continued from creation was divided to produce the hemispheres as we now know them. But notwithstanding this, the geographic location of the Garden of Eden was made known to the Prophet Joseph Smith by revelation as here in the land of America, in Jackson County, Missouri, with Independence as the center place.