Souterrain, a word from French meaning "underground," is a term used by archaeologists to describe a type of underground building linked mainly to the European Atlantic Iron Age. These structures were likely moved north from Gaul during the late Iron Age. Different areas have different names for these structures, such as earth houses, fogous, and Pictish houses. The word "souterrain" is used separately from "fogou," which means "cave." In Cornwall, the local name "fogou" (meaning "cave" in Cornish) is used for souterrain structures. The way these underground buildings were designed varies by region. For example, in western Cornwall, fogous seem to have been used for storing food.
Etymology
The word "souterrain" comes from the French language (sous-terrain or souterrain), and it means "underground passageway" or refers to underground areas in general. In languages other than English, the word is sometimes used to describe a "basement," especially in warehouses or a semi-basement.
Construction and suggested purpose
Souterrains are underground rooms that were connected to a settlement. These rooms were dug out and then covered with stone slabs or wood before being covered back up. If the rooms were carved directly into rock, this covering was not always needed. There is no evidence that souterrains were used for burials or rituals. Some experts think they might have been used to store food or as hiding places during times of conflict. However, some souterrains had entrances that were easy to see.
Examples
In 2016, archaeologists from Headland Archaeology discovered a souterrain with wooden walls and possibly a water tank at Brechin Farm, Angus. The souterrain was 15 meters (50 feet) long and shaped like a "C" with two separate rooms. A straight ditch was found next to the souterrain and connected to the southwest room through a tunnel. The tunnel sloped downward toward the room, and its sides were covered with iron, showing that water had flowed through it for a long time. This suggests the southwest room was used to collect and store water. The souterrain was dug into soft sand, which would have collapsed without wooden walls. Evidence of wooden supports and the absence of stones near the northeast room confirm the walls were made of wood. Radiocarbon dating shows the souterrain was used between the 1st and 3rd centuries AD.
Another example is a souterrain found at Rosal, Strathnaver, Sutherland. No artifacts were found inside, and the roof may have had only partial stone covering, with wooden parts on other sections. Experts think it might have been used as a byre or barn and was linked to an abandoned settlement.
A partially explored souterrain called Castle Bloody is located on Shapinsay in the Orkney Islands, near the coast. Another souterrain was found in Perthshire near Alyth.
In Scotland, some souterrains may have been built by the same people who constructed brochs.
A detailed description of a souterrain at Newtownbalregan, County Louth, Ireland, was published in Archaeology Ireland in the Winter 2003 issue. This souterrain was discovered during a road-building project.
A full report on a three-level souterrain at Farrandreg, County Louth, from 1998 includes information about 14 previously found souterrains in the area. Artifacts found there include a grinding stone, a bone comb, a copper stick pin, three bone needles, and part of a pottery vessel made of "Souterrain ware." Based on these items, the souterrain was likely sealed around the 12th century.
In Ireland, souterrains are often called "caves." A. T. Lucas, a folklorist and museum director in the 1960s, wrote about references to souterrains in early Irish records. Donaghmore Souterrain in County Louth and Drumlohan Souterrain in County Waterford are the only souterrains in Ireland designated as National Monuments.
In Ireland, souterrains are often found near or inside ringforts, suggesting they were built around the same time as these structures, which makes them slightly later than in other regions. This idea is supported by ogham stones from around the 6th century reused as roof supports or door frames, such as at the "Cave of the Cats" in Rathcrogan. Souterrains are unevenly spread in Ireland, with the most found in north Louth, north Antrim, south Galway, and west Cork and Kerry. Fewer are found in Meath, Westmeath, Mayo, north Donegal, and Waterford. Counties like Limerick, Carlow, and Wexford have very few examples.
An article by Warner about souterrains, written 47 years ago, remains one of the best general summaries of the topic.
The most detailed study of Irish souterrains is M. Clinton's 2001 book, which includes chapters on their locations, associated settlements, uses, artifacts, timelines, and 13 sections about their construction.
A brief summary of Irish souterrains was published in Archaeology Ireland in 2004.