Abstract: The High Resolution Imaging Science Experiment's (HiRISE) imagery of Mars allows for meter scale identification of surface features. In this imagery we can identify boulders clustering on polygonal patterned ground terrains in polar environments on Mars. Previously, terrestrial analogs of Mars were used to explain boulder clustering. However, the Mars environment is distinct from Earth's and the boulders that cluster on Mars are at least 3 - 10 times larger than any found clustering on terrestrial patterned ground terrains. Here, I propose a new mechanism for boulder clustering unique to Mars and use observations of boulder clustering around impact features to place constraints on the timescale of boulder clustering.