Observations of some low Mach number collisionless shocks in space have revealed that their associated ion heating is greater than adiabatic, is very rapid, is primarily in the direction perpendicular to the magnetic field, and takes place in the bulk of the distribution. These features are very different from those encountered at crossings of supercritical shocks and not yet fully understood. In this paper we use a one-dimensional hybrid kinetic simulation to study the details of the evolution of the incoming ions across a set of low Mach shocks. We find that the bulk of the ion velocity distribution becomes elongated along the direction perpendicular to the shock front as the ions traverse the shock ramp. The subsequent gyration of the ions in the steady field downstream gives rise to a temperature signature with features that correspond closely to those enumerated above. This suggests that these features may originate primarily from the kinetic behavior of the ions at the shock rather than from the operation of some instability. We also investigate the dependence of our results on a number of physical and numerical parameters in the simulation. ¿ American Geophysical Union 1991