in
Maine resulted from oyster harvesting from to . A
shell midden or
shell mound is an archaeological feature consisting mainly of
mollusc 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. Certain shell middens are linked directly to villages, serving as designated dump sites. In other cases, the materials found in the middens are closely tied to individual houses within the village, where each household would dispose of its waste right outside their home. Regardless of their association, shell middens are highly intricate and challenging to excavate completely and accurately. 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. Shells have a high
calcium carbonate content, which tends to make the middens
alkaline. This slows the normal rate of decay caused by soil acidity, leaving a relatively high proportion of organic material (food remnants, organic tools, clothing, human remains) available for archaeologists to find.
Edward Sylvester Morse conducted one of the first archaeological excavations of the
Ōmori Shell Mounds in
Tokyo,
Japan in 1877, which led to the discovery of a style of pottery described as "cord-marked", translated as "
Jōmon", which came to be used to refer to the period of
Japanese prehistory when this style of pottery was produced. Shell middens were studied in Denmark in the latter half of the 19th century. The Danish word
køkkenmødding (kitchen mound) is now used internationally. The English word "midden" (waste mound) derives from the same Old Norse word that produced the modern Danish one.
Examples shell midden, in
Florida, is the largest on the US East Coast. ,
Chiba,
Chiba Prefecture Japan Shell middens are found in coastal or lakeshore zones all over the world. Consisting mostly of
mollusc shells, they are interpreted as being the waste products of meals eaten by nomadic groups or hunting parties. Some are small examples relating to meals had by a handful of individuals, others are many metres in length and width and represent centuries of shell deposition. In
Brazil, they are known as
sambaquis, having been created over a long period between the 6th millennium BCE and the beginning of European colonisation. European shell middens are primarily found along the
Atlantic seaboard and in
Denmark and primarily date to the 5th millennium BCE (
Ertebølle and Early
Funnel Beaker cultures), containing the remains of the earliest Neolithisation process (pottery, cereals and domestic animals). Younger shell middens are found in
Latvia (associated with
Comb Ware ceramics),
Sweden (associated with
Pitted Ware ceramics),
the Netherlands (associated with
Corded Ware ceramics) and
Schleswig-Holstein (
Late Neolithic and
Iron Age). All these are examples where communities practised a mixed farming and hunting/gathering economy. In 2025,
IIT Gandhinagar researchers have uncovered shell midden sites in
Kutch in India, revealing hunter-gatherer communities lived there at least 5,000 years before the
Harappans. These sites, with discarded shells and stone tools, show early coastal communities adapted to mangrove environments and relied on marine resources. This discovery challenges the idea that Kutch's urbanism was solely externally influenced by
Sindh, suggesting a gradual, locally rooted cultural evolution. On
Canada's west coast, there are shell middens that run for more than along the coast and are several meters deep. The midden in
Namu, British Columbia is over deep and spans over 10,000 years of continuous occupation. Shell middens created in coastal regions of Australia by
Indigenous Australians exist in
Australia today. Middens provide evidence of prior occupation and are generally protected from mining and other developments. One must exercise caution in deciding whether one is examining a midden or a beach mound. There are good examples on the
Freycinet Peninsula in Tasmania where wave action currently is combining charcoal from forest fire debris with a mix of shells into masses that storms deposit above high-water mark. Shell mounds near
Weipa in far north Queensland that are mostly less than high (although ranging up to high) and a few tens of metres long are claimed to be middens, but are in fact shell cheniers (beach ridges) re-worked by nest mound-building birds. Some shell middens are regarded as sacred sites, linked to the
Dreamtime, such as those of the Anbarra group of the
Burarra people of
Arnhem Land. Shell mounds are also credited with the creation of
tropical hardwood hammocks, one example being the
Otter Mound Preserve in
Florida, where shell deposits from
Calusa natives provided flood free high areas in otherwise large watered areas. There are instances in which shell middens may have doubled as areas of ceremonial construction or ritual significance. The
Woodland period Crystal River site provides an example of this phenomenon. Some shell mounds, known as
shell rings, are circular or open arcs with a clear central area. Many are known from Japan and the southeastern United States, and at least one from South America. ==Etymology and usage==