The kinematics and dynamics of thrustbelts have been investigated through a range of two-dimensional models based on the development of thin-skinned thrust wedges by horizontal shortening of sediments. All of them include the effects of gravity and topography, and describe thrustbelts as wedges detached along a basal décollement, which is either pushed forelandward by a rigid buttress in the hinterland (e.g., Chapple, 1978; Cowan and Silling, 1978; Davis et al., 1983; Stockmal, 1983; Dahlen et al., 1984; Lehner, 1986; Platt, 1986; Mandl, 1988; Molnar and Lyon-Caen, 1988; Dahlen and Barr, 1989; Beaumont et al., 1994; Strayer et al., 2001) or is pulled by the subducting plate (Silver and Reed, 1988; Barr and Dahlen, 1989; Willett et al., 1993).

The earliest thrustbelt model described wedge material as being ideally plastic (Chapple, 1978). This material underwent shortening as it advanced in a piggy-back mode, from the back to the front of the wedge. A surface slope, with a critical taper was created, allowing the wedge to experience the plastic yield state and to slide along its décollement towards the foreland.

Subsequent thrustbelt models described deforming material as noncohesive, frictional Coulomb wedges (Davis et al., 1983; Dahlen, 1984) or frictional plastic wedges (Mandl, 1988). Although these models and the previous one differ in the behaviour of the deforming material and the yield conditions, they all describe thrust wedges as tapering toward the foreland. In all of these cases, the wedge would advance if the sum of the basal and topographic slopes reached a critical angle (Fig. 2.1). Other common properties include hinterlanddipping décollement, below which there is little deformation and significant horizontal compression in the wedge material.