Milankovitch ice sheet and Cretaceous sea level models face the same sedimentary problem Ð Same equilibrium and instability Part 2. Presenter: Stuart Gaffin Abstract: Three components define equilibrium and instability for long-standing Milankovitch 100-kyr continental ice sheet models: (i) non-linear surface shape; (ii) two areal zones of mass supply and sink, separated by; (iii) a nearly-horizontal linear mass controlling surface intersecting with the surface. A diagram for this ice sheet system can be simply rotated to model continental margin sedimentary basin systems, with sea level, bedrock erosion and deposition substituting for the snowline, accumulation and ablation. Erosional unconformities provide positive surficial mass supply feedback and instability.