Deep seismic reflection data has shown the importance of low angle faults and detachments in continental extensional tectonics. A quantitative model of continental lithosphere extension is presented, incorporating geometric, thermal and isostatic components. The upper lithosphere extends by simple shear associated with low angle faults, while the lower lithosphere deforms by pure shear. The resulting sedimentary basin geometry and crustal structure are dependent upon the amount of lithosphere extension, the distribution of the pure shear, the depth of the horizontal detachment, the geometry of the low angle fault and the isostatic response of the lithosphere during rifting and thermal subsidence. The Jeanne d' Arc basin, Newfoundland is most closely represented by models incorporating the flexural isostatic response of the lithosphere to applied loading. Stratigraphic data shows that the basin was generated by several pulses of extension and rifting was followed by erosion. Modelling techniques are used to assess the implications of these phenomena. A two dimensional study of the rheological strength of the lithosphere shows it to be determined by the interaction between the pre-rift thermal state of the lithosphere, the position of simple shear deformation with respect to that of pure shear, time since rifting and the rate of extension. Model predictions of lithosphere shortening on low angle thrusts have been combined with the extensional modelling technique to explore the process of basin inversion. Model predictions are compared with observations from the North Celtic Sea Basin. Extension on planar faults is modelled by considering the footwall and hanging wall as two interacting cantilevers, which flex in response to the isostatic forces created during extension. The construction has been applied to extension on a sequence of planar faults and predicts the familiar "domino-style" block rotation.