The structure of the E Greenland coastal flexure, a major structure developed during continental break-up, is interpreted on the basis of field observations. An earlier model, which involves normal inland-dipping, antithetic faulting and seaward rotation of fault blocks is confirmed and amplified. This model requires that regional dips are very much less than dips measured on bedding planes thus leading to considerably reduced thicknesses for the Tertiary volcanic succession in E Greenland. Detailed mapping confirms the validity of these thickness estimates and leads to the conclusion that the volcanic extrusion rate was similar to that of present-day Iceland, thus obviating the need for special mechanisms of magma generation. Comparable structures occur in other regions of continental break-up and voluminous basalt discharge and it is suggested that the flexure developed by collapse of the attenuated crust subsequent to the massive extrusion of plateau basalts.