Stratigraphy is concerned with the attempt to determine a subject’s age by the layer of earth (or strata) in which it lies. This is based on the (generally accurate) assumption that the oldest layer of sediment or debris was deposited first and is therefore situated at the bottom, whereas the youngest will be at the top - this is known as the law of superposition. Violent earth movements such as faulting and folding (especially in matters geological), construction work (in matters archaeological) or something as simple as the collapse of a rabbit’s burrow, however, can distort interpretations and thereby create an inaccurate picture. Due to speculative nature of the process, it is considered a relative dating method, rather than a scientific one.