The sediments carried by the Mississippi River are dropped at the delta. There are sand bars, point bars, old river bows now silted in, a crow's foot of sandy distributary channels, and between channels, swampy flood plains are filled with decaying organic material. The landscape is clearly laterally variable, and eventually it will all sink of its own weight, aided by growth faults and the weight of later sedimentation. After it is buried and out of sight the lateral variations will remain as pods that will be observable by the seismologists of the future. These seismologists may see something like Figure 11. Figure 11 shows a three-dimensional seismic survey, that is, the ship sails many parallel lines about 70 meters apart. The top plane, a slice at constant time, shows buried river meanders. The data shown in Figure 11 is described more fully by its donors, Dahm and Graebner .