How did the geology and geomorphology of a site become the way it is today? And what are the practical engineering geological applications of that knowledge to civil engineering and environmental projects? The answer is much more than a description of the materials logged in an excavation or a borehole, or a description of a site's geological history. It requires a mental time machine that enables us to investigate and understand the conditions, processes and materials that occur over geological time and recently (including human-induced, anthropogenic impacts).In this paper, by means of some short case study examples, I explore and describe how the application of a time machine approach is an essential tool for engineering geologists, both in the field and back at their desks.