A midden (also kitchen midden or shell heap) is an old dump for domestic waste which may consist of animal bone, human excrement, botanical material, mollusc shells, potsherds, lithics (especially debitage), and other artifacts and ecofacts associated with past human occupation. These features provide a useful resource for archaeologists who wish to study the diets and habits of past societies. Middens with damp, anaerobic conditions can even preserve organic remains in deposits as the debris of daily life are tossed on the pile. Each individual toss will contribute a different mix of materials depending upon the activity associated with that particular toss. During the course of deposition sedimentary material is deposited as well. Different mechanisms, from wind and water to animal digs, create a matrix which can also be analysed to provide seasonal and climatic information. In some middens individual dumps of material can be discerned and analysed. A shell midden or shell mound is an archaeological feature consisting mainly of mollusk shells. The Danish term køkkenmøddinger (plural) was first used by Japetus Steenstrup to describe shell heaps and continues to be used by some researchers. A midden, by definition, contains the debris of human activity, and should not be confused with wind- or tide-created beach mounds. Some shell middens are processing remains: areas where aquatic resources were processed directly after harvest and prior to use or storage in a distant location. Some shell middens are directly associated with villages, as a designated village dump site. In other middens, the material is directly associated with a house in the village. Each household would dump its garbage directly outside the house. In all cases, shell middens are extremely complex and very difficult to excavate fully and exactly. The fact that they contain a detailed record of what food was eaten or processed and many fragments of stone tools and household goods makes them invaluable objects of archaeological study.