Casa Montero flint mine
Prehistoric mining in the Community of Madrid
The Casa Montero flint mine (Vicálvaro)
Casa Montero is a flint mine located in the center of the Peninsula, whose exploitation dates back to the beginning of the Neolithic period (just over 7.000 years ago). It is one of the few deposits of this type studied in depth in our country.
It is located in the Municipal District of Madrid and more specifically in the Vicálvaro district. Located on the escarpments of the right bank of the Jarama, in the vicinity of its confluence with the Henares river, it crowns a hill limited by ravines to the north and south and the Jarama valley to the east, while to the west the terrain descends gently forming an extensive plain.
The site has an extension of more than 4 hectares and is made up of more than 4.000 underground structures, most of them Neolithic wells for the extraction of flint, although evidence of other chronologies, from Paleolithic and the Bronze Age to vestiges of mining of recent moments.
Casa Montero Neolithic mining is characterized by the exploitation of underground flint veins through the excavation of vertical wells.
The chronology of this primitive mining has been established by means of absolute Carbon 14 dating made on fragments of charred wood. The results confirm that they are located in the ancient Neolithic (5400 - 5200 BC), which makes Casa Montero the second oldest mine in Europe, after that of Defensola, in the Apulia region (Italy).
The choice of this area by the Neolithic miners was not accidental. On the one hand it would be easy to dig the wells due to the inclusion of the silica veins between levels of clays and on the other hand, the Casa montero flint has a particular genesis that allowed the formation of nodules with qualities that make it especially suitable for size
Extraction wells
To access the underground levels of flint, the main method used in the Neolithic era was to dig deep and narrow wells, very close to each other. The distances between the wells are almost always less than 30 cm. Despite this proximity, the vast majority of wells are not cut. In total, more than 3.794 Neolithic wells for raw material extraction have been identified.
Mining shafts are simple structures, with a reduced diameter, ranging between 0,85 and 1,50 meters in maximum diameter at the mouth. In other European mines, the dimensions are much larger, which facilitated work in groups of up to 20 people. In Casa Montero, on the other hand, only one person could work in each well. Therefore, the minimum mining team would be composed of two individuals, one inside the well and another helping from the outside in the removal of waste, providing tools, etc.
Two types of wells have been distinguished based on their depth and the characteristics of their walls. Irregular wells are those whose depth does not exceed 2,50 meters and their walls are sinuous, sometimes with holes resulting from the extraction of nodules and even with accidental communication through amorphous and narrow cavities.
On the contrary, chimney-type wells have regular walls, with a very vertical tendency and depths that range between 0,45 and 10 meters. Three subtypes can be distinguished depending on the shape of their mouth: cylindrical wells, wells with a bucket mouth, and wells with a funnel mouth.
On the walls of the wells, installations carried out by miners have been documented to facilitate their extractive work. One of these are pates, holes made in the walls used as stairs. Another arrangement consists of two opposite holes of circular section, interpreted as a support for a crossbar used as a pulley.
The narrowness of the wells favored the conservation of humidity and minimized the risk of collapse of the walls. In fact, not only have no landslides been identified, but the walls of the wells have been found in very good condition, with no evidence of erosion, despite the time that has elapsed. This suggests that the wells were intentionally filled shortly after being excavated. Well fills mainly contain sediment extracted from themselves and wastes from the extraction and carving processes of flint. Everything indicates that after the excavation of the wells and the extraction of the raw material, the carving was carried out in the vicinity of the wells and that the residues of these activities were thrown into the wells. This practice would be an efficient way to manage the large volume of debris generated while ensuring the safety of those who moved on the surface, since otherwise they would have run the risk of accidentally falling into open pits.
Unlike in the European prehistoric mines where most of the extraction related tools are made of horn or bone, whether they are horn picks or shovels made with animal scapulae, at Casa Montero these are very rare, with more abundant stone ones.
The tools can be classified into two large groups, depending on the activity for which they are intended: a first group used for the excavation of wells (picks, maces, wedges) and the extraction of flint blocks (large hammers) and a second group of tools for the maintenance of the mining operation (scrapers, denticulates).
The mining tools were made from materials brought to the deposit, as is the case of the quartzite ridges from the banks of the Jarama, destined for maces and large hammers, or they may come from debris from the flint carving itself mine, as occurs with spikes and wedges.
The maces were possibly used to strike wedges or picks that penetrated the earth like a chisel. The wedges would be used to remove nodules and the picks would be used to excavate the wells
In addition to extracting the flint, the carving of this material was carried out in the mine itself, an activity that generated an enormous volume of remains. 338 tons of flint have been obtained from the 65 wells investigated, the majority of these pieces being remains of stature.
It is known that the extraction of the stone and its subsequent carving was an occasion to bring together the small human groups in the region, the first to engage in agriculture. The complex work of extraction and production of flint tools gave cohesion to the inhabitants of these lands, creating new and extensive social ties between them.
In this context the learning of lithic carving took place. For the first time in a flint mine this process has been documented by identifying three skill levels among carvers (master, advanced learner, and initial learner). Children (3-7 years old) would help in the tasks of sleeving, waste management or flint acquisition in the outcrops. Starting at 7 or 8 years old, young people would start carving.
At Casa Montero all the categories of the Lithic Operational Chain have been documented, from the supply of raw material, devastated, finished and used, to abandonment.
Image gallery
Archaeological performance
The mine was discovered in September 2003 during the mandatory archaeological surveys carried out prior to the construction of the Third Madrid Ring Belt (M-50).
Given the uniqueness and importance of the site, the General Directorate of Historical Heritage of the Community of Madrid determined the modification of the road layout, which, moving 60 meters, allowed the area with the highest concentration of remains to be preserved.