After a certain period of time, a well falls out of use. This can be for the simple reason that the well has dried up. Other possible reasons can be pollution of the water, or moving away of the users (Schinkel 1994 II, 180). A fourth reason is when the well construction caves in. When a well falls out of use, part of the construction, if still of good quality, may be dug up for reuse. When a well has collapsed, then it can sometimes be repaired.
When a well is no longer used, it will fill up sooner or later. This can happen in different ways, for instance slowly by natural causes, quickly by deliberate filling up, or suddenly when the well collapses. The fill layers often reveal the way in which a well is filled. The top layer of a well – the top fill – is of a later date than the rest of the fill, whether the well has filled up slowly or quickly. This is a result of the compaction of the main fill, resulting in a depression at ground level. Such a depression can last for years, but will eventually be filled up as well.
The chance of materials entering a well after it has fallen out of use is high. First of all, materials can enter the well when the construction is dug up. The most obvious examples are parts of the construction or tools, but other items can also end up in the pit. An example consists of two brooches found in a deconstruction pit in Geldermalsen (Van Renswoude & Roessingh 2009, 595). Furthermore, when the construction has been dug up, and the well is no longer closed off or protected in other ways, all kinds of stray rubbish can fall in the shaft, such as pottery sherds, animal bones, charcoal and stone. At this moment, small animals can also fall into the well. Examples are known of wells or steep-sided pits with large amounts of remains of frogs and mice that were unable to climb out of the well.
Finds can also enter the well when it is filled deliberately. This can either be accidental (stray rubbish or lost items) or on purpose. In some cases, wells were not only filled with soil, but also with rubbish. A well that has fallen out of use can be used secondarily as a rubbish pit. In that case, the shaft is also filled up with rubbish, but the filling of the well is not the primary goal; moreover, the filling up would take place over a longer period of time. Most archaeologists have no doubts about former wells being used as rubbish pits, but there is uncertainty about how to recognise a rubbish pit (Therkorn & Besselsen 2008, 243). It seems likely that a rubbish pit contains large amounts of settlement rubbish of all kinds, such as pottery sherds, building debris, stone, glass, wood and animal bones. Rubbish should be broken or fragmented and no longer of use (Groot 2009b, 390).
Finds from the top fill seem to constitute a separate category. As described above, the soil in the fill of a well is compressed over time, causing a depression on the ground surface. Such a depression will function as an artefact trap: stray rubbish will end up in the depression and remain there. This depression can exist for decades, and collect all sorts of materials. For instance, pottery from the Middle Roman period and Early Middle Ages was found in a well in Breda, which dates to the late Middle or early Late Iron Age (Berkvens 2004, 132-133). In this case, the depression lasted for centuries. Finds can also be placed in the top fill on purpose. In Geldermalsen, for example, a dog was buried in a depression left by an old well (Van Renswoude & Roessingh 2009, 596). A practical reason for this could be that it was more convenient than digging a pit, although the dog still had to be covered with soil.
In this discussion of what kinds of materials can end up in wells, a functional explanation has been the basis, and only the objects that can be expected to enter wells during normal use have been discussed. Below, we will offer an alternative explanation for many of these finds. Before we can look at more special finds from wells, and discuss whether these should be interpreted as rubbish, accidental loss or as ritual deposits, we must discuss how we can make this distinction.