Image Credits: Figure 9 from McPhillips and Brandon, this issue, p. 90–116. Forward model results for the best estimate parameter values. Exhumation is defined as the sum of surface and rock offset and is accomplished by erosion. Surface offset is the sum of the parameters relief and rampElev. Rock uplift is given by the parameter tectonicUplift plus any flexural adjustments (fig. 6). The grid shows these sums graphically at each topographic state. The difference in the transparency of the color scheme shows the map area where we have elevation control (that is, between the eastern boundary of the Great Valley and the Eastern Escarpment).