The concept of depositional episodes and the depositional systems basin-analysis method were developed largely in the Gulf Coast region as a means of analyzing and interpreting the immense thicknesses of sediment there that are so rich in oil and gas. The principles of the depositional system have never been formally stated, although they have been widely used, particularly by geologists at the Texas Bureau of Economic Geology (e.g., W.L. Fisher, L.F. Brown Jr., J.H. McGowen, W.E. Galloway, and D.E. Frazier. See selected references quoted in Section 1.2.2). Other geologists who made notable early contributions in this area include R.J. Weimer, D.A. Busch, J.C. Crowell, J.C. Ferm, H.A. Lowenstam, N.D. Newell, and H.R. Wanless.