Was All of South America Underwater?

All geological drawings and reports regarding ancient South America show that the central lowlands, referred to today as the Amazon Drainage Basin, was underwater. This region covers an area of about 2,400,000 square miles, or about 35.5 of the entire South American continent—an area a little smaller than the contiguous United States or Australia. It is located in the countries of Bolivia, Brazil, Colombia, Guyana, Suriname, Venezuela, eastern Peru, and eastern Ecuador. Today, this area is covered with the largest rainforest in the world.

A tepuis table-top Craton on the Guiana Shield. It sticks above the clouds as it once did above the ocean that surrounded it

Other areas, known as Cratons were above water, though not necessarily very high and certainly not at the elevation known today. Running from the western Andean region of today, the Amazon River runs about 4,000 miles before it drains into the Atlantic Ocean; however, before the Basin rose out of the Atlantic, the river ran a short distance and emptied into the eastern sea, named by geologists as Mar Pebesiano, or Pebesian Sea,part of the “Marine Ingression,” which inundated the lowlands of Brazil and the drainage basin.
    The land that was not submerged was the entire Western Andean Shelf running from Colombia southward through Chile where it broke up into a myriad of islands now known was the Lake District—a landscape of rivers, lakes, volcanoes and forests. That emerged land was along the Andean Shelf, from around southern Colombia to southern Chile, just south of Santiago, and much of the eastern shore from Montevideo in Uruguay to around what is now the mouth of the Amazon River. North of the Amazon Seaway, which followed the course of the present river through to the Atlantic, was emerged land making up the Guayanan Shield
    The term Guiana or The Guianas is often used as a collective name for Guyana, Suriname an French Guiana, and sometimes even includes the portions of Colombia, Venezuela and Brazil, which are on the Guiana Shield. It is one of three cratons of the South American Plate, forming a portion of the northeastern coast. The higher elevations on the shield are called the Guiana Highlands, which is where the table-like mountains called tepuis are found. A 12-square mile summit area is bounded on all sides by cliffs rising 1,300 feet and forms the tripoint of Venezuela, Guyana and Brazil atop Mount Raoraima.
    There it rains almost every day of the year. Almost the entire surface of the summit is bare sandstone, with only a few bushes and algae present, the top itself consisting of greenstones, quartzites, shales and conglomerates intruded by sills of younger mafic intrusives such as gabbros (Allen K. Gibbs and Christopher Norman Barron, The Geology of the Guiana Shield, Oxford University Press, Oxford, UK, 1993).

The three main (circles) Cratons or Shields of South America and the Andean Shelf running north and south along the shoreline were all that was above water—the rest of South America was submerged

South of the Guiana Shield is the Brazilian Craton, a similar, though greater, shield that occupies a large portion of the central, north and eastern part of the continent. The Guiana Shield and and this Central Brazil Shield (Guaporé Shield) constitutes respectively the northern and southern exhumed parts of the overall craton.
    Exhumed, or denudation, involves the processes that cause the wearing away of the Earth's surface by moving water, by ice, by wind and by waves, leading to a reduction in elevation and in relief of landforms and of landscapes Endogenous processes such as volcanoes, earthquakes, and plate tectonics uplift and expose continental crust to the exogenous processes of weathering, of erosion, and of mass wasting or movement.
    These stable portions of the continental crust, with the basement rock crops out at the surface, and platforms, in which the basement is overlaid by sediments and sedimentary rock. Stated differently, a Shield is a solid, foundation rock base, or continental block, to a solid geologic formation. As such, these Cratons or Shields remain intact despite other forces around them. Thus, in South America, these higher land forms were always above water when the Amazon Drainage Basin was submerged.
    As for the Brazilian Shield, it is a pre-cambrian geologic formation lying primarily south of the Amazon River. The ancient sedimentary rocks of the Brazilian Shield are well weathered, and the tributaries draining them tend to be nutrient-poor ‘clearwater’ rivers, which appear transparent. In fact, hundreds of rivers and streams flow through this area on their way to the Amazon.
    Despite the low nutrient content of the water, these rivers are believed to contain exceptional levels of aquatic diversity, with a large number of migratory fish species. As the rivers and streams near the Amazon, they swell and pick up speed. At one point, the mighty Madeira River rushes through 200 miles of deep, swirling rapids.

The two exposed Cratons appeared as large islands in the midst of the sea, though uninhabitable, why the Andean uplift was habitable being mostly grass lands and forested

This Brazilian Shield, much larger than the Guiana Shield, is further south, though each is slightly different, since the exact boundaries of the Shields , which were completely surrounded by the sea, are a matter of speculation in exact size. Anciently, the submerged Amazon Basin surrounded the Guiana Shield, forming a distinct island above water at one time of several square miles. The Brazilian Shield was not as distinct, having highs and lows in the Craton or rock shield. The separation between the two Shields is the Amazon River mouth today, but in ages past was merely a wide opening between the two islands.
    The rise of the Andes changed the drainage of Amazonia causing the formation of the     modern mighty river system. This period was also a time of a marine highstand with sea-level probably at its highest, which high stand coupled with forebasin downwarping, resulted in extensive epicontinental seas within Amazonia. While some debate exists regarding the full extent and connectivity of these water bodies, it is apparent that they would have been potentially much greater barriers to dispersal than any modern river of the Amazon Basin. Much of the proto Andes would have supported lowland forests prior to the mid-Miocene and these areas may subsequently have provided species for the expanding western Amazon forests that colonized land left by falling sea-levels.
    With the rise of the eastern continent, which still tilts toward that rise from west to east), the waters in the west began rushing toward the eastern edge of the rising land, forming rivers and deep cutting beds. Before that time, it was more like the ocean with water setting and moving gently with currents.

The various depressions/basins that create the lowlands of  South America, all of which make up the Amazon Drainage Basin, which was underwater before the warping and uplift of the Andes Mountains

The Pebesian Sea is the result of the Pebas/Solimōes Formation, a lithostrtigraphic unit found in western Amazonia and extended over 390,000 square miles, including parts of Brazil, Peru Ecuador and Colombia. This area, being part of a series of Pebesian lakes formed within the foreland basin of the Andes mountain belt (Frank P. Wesselingh, et.al., “The stratigraphy and regional structure of deposits in western Amazonia, Scripta Geologica, vol.133, Netherlands, 2006, pp291-322), and became the Pebesian Sea until the central lowlands of South America emerged from the sea as at the time of the upwarp of the Andes.
    The Paranense or Entrerriense Sea was a epicontinental sea overlying the continental shelf as part of the open ocean. During the transgression of the Atlantic, when several of these epicontinental seas merged and then later drained at the time of the Andes upwarp, which caused the emergence of such areas as the Buenos Aires high, the La Pampa Central block, and the San Rafael block. The sedimentation of the Neogene continental succession started after the regression of the Paranense Sea.
    Lineages previously to the west of the Pebasian and Paranense Seas, and separate from eastern Amazonia, might account for the basic east-west biogeographic split in some Amazonian clades. Similarly the seaway or the great wetlands if this were not an actual sea, that lay in the modern Amazon channel could have provided the basic north-south discontinuity.
    As a result of all this, we find that the continent now known as South America, was mostly underwater, whether because of high sea levels or some other reason, and only the western Andean Shelf and the three major Cratons encompassing most of the eastern shore line, were above water.
    Thus, we find that at one time that area of South America referred to as the lowlands or Amazonian Basin was part of two seas, both emptying into the Atlantic as they swirled around the three major Cratons of the continent. When the seas lowered, either globally or by the land form rising, the inland waters were tilted eastward and emptied into the Atlantic, forming rivers throughout the inland, most emptying into the Amazon River, whose depth even today is quite minimal throughout most of the Amazon Basin.
    While it may be difficult for those who are not familiar with the time frame of the warping of the Andes and the settlement and rising of Amazonia, it might be hard to imagine the changes being discussed. However, as difficult as it may be for some, the science is specific though time frames vary, that the middle or central part of South America was originally submerged, and rose with the warping or uplift of the Andes
    Others may have difficulty with the short time frame in which these mountains were created and the Basin uplift, but we have the Lord’s word it took place (3 Nephi 8:10,12, 14, 17-18; 9:12). We also know it was prophesied to take place as Samuel the Lamanite stated: “And behold, there shall be great tempests, and there shall be many mountains laid low, like unto a valley, and there shall be many places which are now called valleys which shall become mountains, whose height is great (Helaman 14:23). And all of this took three hours according to the Disciple Nephi (3 Nephi 8:19).