I am not a geologist. My specialized training is in finance and law, but I've taken what amounts to a supermajor in a wide variety of scientific fields. I don't know about the particular data you are referring to. However, in the Western United States, there used to be several supermassive lakes, such as Lake Bonneville and Lake Missoula. During and after Noah's Flood, the plates underwent enormous upheaval, causing the rising and sinking of large sections of the crust. The Rocky Mountains are an example, and a tremendous amount of left-over water was trapped in certain bowls. The water was augmented by the massive amount of precipitation that followed the Flood, since ocean waters were extremely hot and gave off large amounts of precipitation, which came down as snow and rain in the upper latitudes and the mountain areas and causing the Great Ice Age. As the ice caps rapidly moved south (and north), they both caused and breached the bowls containing these huge inland lakes, causing floods that carved out the Columbia River Gorge near my hometown, and the Grand Canyon, for instance. Charles Darwin observed such a breach point in South America, but improperly attributed it to gradual erosion from rivers. My sequence of events may be off, but you can get the general idea here: http://www.hugefloods.com/. The evidence for massive post-Flood floods in various regions of the world is quite manifest.