Heart Mountain, Wyoming, USA, is a geological puzzle. Paleozoic carbonates overlie much younger Lower Cenozoic rock. So, either several mountain-sized blocks broke apart and slid up to 45 km from where they were originally deposited onto the younger rock or the way the relative ages of the base layer and the blocks are assessed is wrong. This paper, with its partner, examines the issues and problems explaining this proposed event. Part I examines three (uniformitarian) models of a low angle slide on a low-friction cushion. In Part II, another six essential issues, including how the movement started and was sustained over uneven terrain, are examined. The joint conclusion is that present models are seriously inadequate.