NORTH AMERICA/Continental Interior 31 Figure 12 Burial history diagram of the Salina Basin (central Kansas; for location see Figure 13 Diagram shows amount of sediment deposited and amount removed giving depth of burial of sediments (From Newell and Hatch (1997) Kansas Geological Survey Bulletin 240.) The diagram illustrates that the basin sub sided and received sediments from Late Cambrian to end of the Devonian when it was uplifted Major subsidence commenced in the Mississippian, with minor uplift near end of the Mississippian and continued from then, with minor ups and downs until the present Figure 11 Example of Pennsylvanian megacyclothem from Kansas, showing individual cyclothems in the Oread Limestone Formation (Virgilian, Pennsylvanian) (Adapted from Merriam (1963) Kansas Geological Survey Bulletin 162.) of the Precambrian, the Ouachita Orogeny (Mississippian), the Allegheny or Appalachian Orogeny (Late Palaeozoic), and the Laramide Orogeny (Cretaceous) An important part of the story on the structural development of the Continental Interior is knowing how deep and when the sediments were buried The ups and downs of the craton at any location is profiled by constructing a two-dimensional burialhistory diagram (Figure 12) Another question is how much material was removed at an unconformity There are numerous ways in which this can be done, but a combination of several approaches for any area is the most satisfactory (Table 1) This information then can be used together with the sediment distribution to understand the history Cratonic Structures The sediments are preserved more completely in the basins than on the adjoining uplifts, as would be Table Different procedures used to determine overburden removed (Adapted from Merriam and Forster (2001) Kansas Academy of Science Program and Abstracts.) compaction depth relations vitrinite reflectance oil field overpressure maturation models thermal modeling mineralogy and rock textures of intrusives fluid inclusions geologic restoration expected The major basins, uplifts, and structural discontinuities in the Continental Interior are shown in Figure 13 A series of cross-sections of the Continental Interior are shown in Figure 14 These cross-sections give the best impression of the subsurface layer-cake nature and the relation of stratigraphic units to one another Most impressive is the thinness of the sedimentary cover (when viewed in perspective (Figure 15); indeed, the sediments are but a facade over the Precambrian foundation The structures shown in Figure 13 are those that formed near the end of the Mississippian and in the Early Pennsylvanian during the Alleghany/Appalachian orogenies and since have been slightly modified