Understanding Megalithic Constructions: Menhirs and Dolmens
Megalithic Construction Types
1. Menhirs
The menhir is the simplest type of megalithic monument. It consists of a stone, of variable shape and height (1 to 6 m), fixed on the ground. Some menhirs stand isolated. The most significant example is in Locmariaquer (in Morbihan, France), which was a 23 m tall simple Menhir.
Menhirs may also appear clustered, distributed in rows, forming alignments, characteristic of Brittany. The best-known alignment is at Carnac, where thousands of standing stones are arranged in eleven rows, decreasing in height. In Britain and Ireland, menhirs are grouped into cromlechs, a curvilinear layout. Many scholars believe these were located in clearings, providing space for community meetings. Since the 1940s, some scientists have linked them to astronomical observations and solar worship.
2. Dolmens
The dolmen, from the words dol and men meaning stone table, is a mortuary building consisting of at least one burial chamber (for incineration or burial) that can be circular, rectangular, or polygonal. Dolmens vary significantly based on the construction of their walls, the elements of their layout, and their roofing systems.
Regardless of type, the construction process of a dolmen typically follows these steps, with the first five involving excavation:
- Grading and ground search for the dolmen site.
- Redesigning the movement and extraction of land created by the excavation of the dolmen floor.
- Containment of pushes from the field through trench shoring.
- Lining (with large stones, masonry, or orthostats).
- Filling the excavated area with the extracted lands.
- Covering the dolmen in its entirety.
- Topping the mound with an exterior cairn for containment of thrust.
- Extraction of land inside the dolmen.
Construction Parameters of Dolmens
Some dolmens were constructed using large orthostats (large stones in a vertical arrangement), while others were built with masonry (either dry stone or with clay mortar). The walls of the Menga cave (Antequera, Málaga) use large, smoothed limestone orthostats, while the Dolmen de Soto (Trigueros, Huelva) uses granite, sandstone, and slate, some with taped signs. In other dolmens, masonry was used, such as in La Pastora, where slate flakes are locked with mud mortar.
Elements of Dolmen Layout
There are three types of dolmens: simple or chamber dolmens, corridor dolmens, and gallery dolmens.
Simple Dolmen or Chamber
The simple dolmen or megalithic cist is small and opens directly to the outside. They are the most numerous, with an estimated 40,000 to 50,000 examples. Initially, it was thought they were covered by a mound of earth, sometimes bounded by land. It is now considered that they could also appear exposed.
Corridor Dolmen
In the corridor dolmen, the chamber communicates with the outside via a corridor of variable length and limited width. The Dolmen de Soto and the Cueva de Menga are representative examples in the southern peninsula.
Gallery Dolmen
In the gallery dolmen, the distinction between the chamber and corridor is limited or nonexistent. The length of the chamber, with parallel walls, is much greater than the width. These dolmens are less common, with Viera’s dolmen being a notable example.
Dolmen Cover Systems
Dolmens can be covered with flat slabs or corbelled masonry. There is no required correspondence between the facing material and the method employed. However, the dolmens of false vault (Tholos), which appeared in the Chalcolithic period (2500 BC, Copper Age), seem to follow a certain pattern.