It often surprises people to learn that excavation is a destructive process that is different from other destructive processes (erosion, vandalism, mechanized earthmoving) only if archaeologists can maintain control and document the process through extensive note taking. This is especially true when it comes to knowing the location (provenience) of artifacts and features. By establishing vertical and horizontal control scientists are able to determine which artifacts and features are related to one another and which are not. This is especially critical when we consider that humans tend to locate themselves in the same places through time. One example might be that different groups of people from different cultural traditions decide to use the same area because of a spring or seep. With each occupation different artifacts and features are added to the archaeological record of a particular place. By establishing horizontal and vertical control scientist's can reconstruct the sequence of events.
Written documentation is key to this process and University of Utah field school students learn a detailed and repetitive style of note keeping called the Feature System. Once a site is "destroyed" by the excavation process only the information captured in the notes remains. For this reason, great care and attention to detail is absolutely essential. Before the first shovel of dirt hits the screens many hours of planning and preparation are required to ensure that the process will run smoothly and, more importantly, that recovered data are complete and accurate. Frequently excavation stops so that notes can be updated and photos taken.