Abstract: A large-scale `in-situ` shear test, employed in the construction of a Brazilian power-navigation projecton the Parana River, was analyzed by a "discontinuum" finite element approach. This was considered particularlyappropriate for simulation inasmuch as horizontal and vertical displacements were recorded as a function of appliedload at a number of points on the test block. In the field test, described in detail by Ruiz and Camargo (1966),resistance between sandstone and an overlying basaltic flow was determined. Inversion of vertical displacementsobserved by Ruiz and Camargo in their field test, are also seen in the theoretical results obtained by the finite elementapproach. However, the theoretical results suggest that inversion of vertical displacements can also occur as a consequence of elastic deformation. The inversion effect can be produced as a consequence of the reorientation of the elasticdisplacement field during the progressive slip along the base of the shear block.