Pastoral Practices, Bedding and Fodder During the Early Neolithic Through Micromorphology at Cova Colomera (Southeastern Pre-Pyrenees, Iberia)

4.1 Burned Dung Deposit

It is located at CE14 level in sector X-32/33, and from the bottom to top, the following microstratigraphic units appear (Figure 3a):

1. Organic residues. Thickness 3 mm. Spongy/massive microstructure and 5% porosity. It is formed by a series of parallel oriented organic residues that in plane-polarized light are yellowish brown in color, probably grass fiber and rich in silica phytoliths (Figure 3b–d) and amorphous organic matter. In grid square X-33, very well-preserved leaves (Figure 4a and b) appear which, due to their morphology, correspond to box (Buxus sempervirens).

2. Charred residues. Thickness 3 cm. Single grain/spongy microstructure and 15% porosity. At the bottom, it appears partially burned, and toward the top, it is carbonized, exhibiting a brown or blackish color in PPL (see Figure 3b) almost isotropic in XPL. It consists mainly of grassy remains of leaves and perhaps stems (Figure 5a and b) and conifer twigs, some with bark (Ismail-Meyer, 2017), needles of Pinus probably sylvestris (Figure 5c) in cross section (Bracegirdle & Miles, 1975), and also, possibly Fagus sylvatica twigs (Figure 5d) (Zibulski & Schweingruber, 2018), as suggested also by K. Ismail-Meyer (University of Basel, personal communication). Some burnt fragments of excrement show a convoluted fabric, suggesting sheep/goat origin (Bergadà, 1998, Courty et al., 1991).

3. Mineralized residues (Ash). Thickness 15 cm and grayish in color in PPL. The unit consists of micritic calcitic accumulations with some sandy particles mainly of quartz and bioclastic limestone gravels with traces of thermoalteration. It has a massive microstructure and 2–5% porosity. Among the main components, we highlight prismatic calcium carbonate pseudomorphs (Figure 6a) from woody plant remains (Brochier, 1996) and multicellular phytoliths (anatomically connected from the husk of grasses) (Figure 6b) as suggested by M. Portillo (CSIC, Institució Milá Fontanals of Barcelona, personal communication). To a lesser extent, there are calcium carbonate pseudomorphs of druses (Figure 6d) that are abundant in leaf remains (Brochier, 1996) and also cellular relicts and wood charcoals. There are also some sheep/goat excrements (Figure 6c) with fecal calcium spherulites inside, some of which have carbonized organic coatings that blacken their surface (Figure 6e) (Brochier, 1996; Polo Díaz, 2010) due to thermal alteration and are known as darkened spherulites. In some cases, the presence of calcium oxalate druses has been observed inside the excrement (Figure 6e). This unit has the most excremental aggregate remains. Fragments of egg shells and bones with traces of combustion, some of which are teeth, also appear among the groundmass.

Figure 3

Burned dung deposit, CE14. (a) Thin section of sample 1 with the microstratigraphic units located. Transmitted light scan. (b) Detail: (1) View of organic residues and (2) charred residues, note that the lower, brown part is partially burnt, and toward the upper, black part, it is more charred, and CE15a, organophosphate clayey silty sands, uncarbonized plant remains reddish-brown (arrows). PPL. (c) Organic residues: oriented parallel organic residues, probably grass fiber. PPL. (d) Detail of silica phytolites (arrows). PPL.

Figure 4

Burned dung deposit, CE14. Organic residues. (a) Field. X-33 grid square. Leaves of box. (b) Detail of leave of box OIL.

Figure 5

Burned dung deposit, CE14. Charred residues. (a) General view. At the top mineralized residues (ashes). In the central part of the image: (1) conifer twig (with bark) in cross-section; (2) surrounded by grassy remains; and (3) cross section of probably Fagus sylvatica twigs. PPL. (b) Grassy leaves. The “skulls” structures are characteristic leaf veins (detail, arrow). Cross-section. PPL. (c) Pine needles in cross section. PPL. (d) Cross section of Fagus sylvatica twig with bark layer (arrow). PPL.

Figure 6

Burned dung deposit, CE14. Mineralized residues. (a) Prismatic calcium carbonate pseudomorphs (circle). PPL. (b) Multicellular phytoliths (anatomically connected from the husk of grasses). PPL. (c) Sheep/goat excrement. The dense outer rim can still be seen, especially in the darker colored lower part (arrow). PPL. (d) Detail. Ashy matrix. Note calcium carbonate pseudomorph druse (P) and prismatic calcium oxalate (O) in the blue box in (c) XPL. (e) Detail of matrix sheep/goat excrement. Fecal calcium spherulites (S) and some darkened spherulites (D) and calcium oxalate druses (arrows) in the red box in (c). XPL.

4.2 Unburned Dung Deposits

They are located in sector X-32 sublevel CE15a with an average thickness of 3 cm and in sector W-31 at the top of a sublevel in CE13, with an average thickness of 8 cm. They are formed by a matrix of organophosphate clayey silty sands (in profile W-31 with predominance of sandy silts) (Figure 7a) and gravels of bioclastic limestone with traces of dissolution. The mineralogy is mainly made up of quartz, calcite, and feldspar. They have a massive/spongy microstructure, and the c/f-related distribution is monic/porphyric, with 5–10% porosity and with undifferentiated and calcitic-crystallitic b-fabric. Plant residues appear in plane polarized light as yellowish brown to red, some of which are partially decomposed, among which conifer wood has been distinguished (Figure 7b and c) and also some possible fragments of seed coats. The outstanding component is very well-preserved sheep/goat excrements, in which even the rims are preserved (Figure 7d) especially in the sublevel top in CE13 (profile W-31). They are brown (PPL) with an isotropic groundmass (Figure 7e) and a relatively high porosity that is characterized by rounded macropores (Figure 7d). They do not appear compacted and fissures are not observed, which indicates that there are no significant traces of trampling. In the interior of the excrements, some of the vegetable waste consumed has clearly been preserved, such as elongate phytoliths and short cells (rondels from Pooideae grasses), and phytoliths from the leaves and culms of grasses (personal communication Marta Portillo) (Figure 7f and g). The fecal calcium spherulites have not been preserved, most probably due to the degradation of organic matter that releases acids and can cause the dissolution of calcium spherulites (Shahack-Gross, 2017), as well as the limestone detrital material. These conditions would also not favor the presence of calcium oxalate crystals due to their decomposition by microorganisms from decayed organic material (Brönnimann, Ismail-Meyer, Rentzel, Pümpin, & Lisá, 2017a).

Figure 7

Unburned dung deposit. Sublevel CE13. (a) Thin section of sample 3. Detail of groundmass: organophosphate clayey sandy silts and sheep/goat excrements (E), most retain a dense outer rim and uncarbonized plant remains (P) reddish brown in color, some of which are wood (P1). Transmitted light scan. (b) Possibly conifer wood (P1) of (a). Oblique section PPL. (c) Detail of the red box of (b). View of xylem tissue with tracheids. PPL. (d) Sheep/goat excrement with dense rims (E1) of (a). Rounded macropores are also observed in its interior (arrows). PPL. (e) Same as (d) showing zones with undifferentiated b-fabric corresponding to organophosphate fine material. XPL. (f) Elongate phytoliths and short cells (rondels from Pooideae grasses, arrow) in the red box in (d). PPL. (g) Phytoliths from the leaves and culms of grasses, arrow, in the red box in (d). PPL.

Among the pedofeatures, we also highlight the appearance of yellow cryptocrystalline hypocoatings in the limestone material in both profiles, but especially in profile W-31. These hypocoatings derive from the decomposition of organic waste, in this case, plant debris and excrement, which react with the limestone material and produce a replacement of calcite by apatite (Karkanas & Goldberg, 2010).

4.3 Reworked Dung Deposits

They are located in sublevel CE15a and in a sublevel of CE12 both in the W-31 profile.

Sublevel CE15a has an average thickness of 8 cm, is formed by organophosphate silty clays with some sandy particles, and has a spongy microstructure with a porosity between 5 and 10%. The components include plant cell tissues, sheep/goat dung in an inclined and vertical arrangement without any trace of combustion, bat and bird fecal remains, and bird’s eggshell fragments. Yellow cryptocrystalline hypocoatings appear in the limestone material. The sublevel appears reworked by water circulation in a laminar sheet of water giving rise to very thin laminae or couplets.

In the bottom part of the CE12 level, there is a sublevel that has an average thickness of 8 cm and is composed of a matrix of sandy silts with stones and gravels of bioclastic limestone with subrounded and subangular morphology. It has a massive/intergrain microaggregate microstructure with 15–20% porosity and a single space porphyric and chitonic c/f-related distribution. The layer is poorly sorted. Among the components are wood charcoals, calcitic ashes, articulated silica phytoliths, sheep/goat dung with traces of combustion, and some bone remains. Some excremental fragments also appear, perhaps from a carnivorous animal. They are characterized by a cemented amorphous yellowish-brown groundmass under PPL that is isotropic in XPL and contains coarse bone fragments (Brönnimann, Pümpin, Ismail-Meyer, Rentzel, & Égüez, 2017b). In general, the arrangement of the components is either inclined or vertical. Among pedofeatures, we highlight silty clay coatings around stones and gravels (170–240 µm), a feature that would indicate displacement (Bertran & Texier, 1999). We believe that a process of mass displacement would have taken place after the combustion of the pen residues, which would cause the secondary position of the stabling episode and some other sporadic occupation of carnivorous in the cave.

5.1 Stabling Practices

Two types of deposits related to stabling activity have been documented: some with combustion and others without.

The accumulation with combustion in situ has been located in sector X-32 and specifically at level CE14 dated c. 5250–5010 cal BC. It has also been located in sector W-31 in sublevel in CE12 dated c. 5060–4780 cal BC with evident traces of reworking.

We will focus mainly on the accumulation located in sector X-32, which has allowed us to locate three microstratigraphic units: organic residues, charred residues and ashy residues. This succession corresponds to a single episode of stabling and burning. The waste that appears at the bottom and in the intermediate zone appears partially burned or charred due to a lack of oxygen (Brochier et al., 1992; Mentzer, 2014). The temperature reached at the top of the zone is higher as a result of better oxygenation, which transforms the fuel into ash that gives rise to the top layer. Of the three units, the lower unit with organic residues, and the intermediate unit, which is charred, are made up mostly of plant remains that are very well preserved and undisturbed. They are mainly made up of grassy remains (leaves and stems) and to a lesser extent conifer and possibly Fagus sylvatica twigs, as well as needles of Pinus probably sylvestris and leaves of Buxus sempervirens.

The top unit is composed principally of a micritic calcitic accumulation in which we highlight multicellular phytoliths (anatomically connected from the husk of grasses), prismatic calcium carbonate pseudomorph from woody remains, a few calcium carbonate pseudomorphs of druses, wood charcoals, and the presence of sheep/goat excrements.

From the documented plant remains, we believe that the bedding and fodder of the stabled ovicaprines were mainly made up of monocotyledonous grass plants. To a lesser extent, there are remains of woody plants, one which is worth mentioning is the presence of several leaves of the box (Buxus sempervirens).

The use of the box was usual in NE Iberia during the 5500–4000 cal BC period. In the site of La Draga (Banyoles, Girona) from Early Neolithic, box leaves have also been found and their presence has been associated with the branches used to manufacture utensils, but they could also be used medicinally (Piqué et al., 2018). Palynological and macrofossil studies of Myotragus balearicus Bate coprolites also prove that the box, specifically Buxus balearica Lam, was part of their diet, namely, the flowers and presumably tender leaves, data that would surprise researchers because of the poor digestibility of the plant (Alcover, Pérez-Obiol, Yll, & Bover, 1999; Welker et al., 2014). In our case, their presence could be intentional; since, traditionally, at least until the middle of the nineteenth century, the leaves and new shoots of the box were used as bedding and they also became a good fertilizer for the fields afterward (Rozier, 1843).

The sheep/goat excrements appear mainly mineralized, and they are characterized by the presence of fecal calcium spherulites with traces of combustion, a very favorable medium for their conservation as it transforms the mono-hydrocalcite into a more stable mineral such as calcite (Canti & Brochier, 2017; Shahack-Gross, 2017). Some of them appear darkened at temperatures between 500 and 700°C (Canti & Nicosia, 2018), and this suggests that temperature was reached in such combustion. From the features observed, it appears that this area was burned at the end of the stabling episode to most probably reduce the volume of waste and also to sanitize the pen (Boschian, 2017; Brochier, 2002; Brochier et al., 1992; Macphail et al., 1997).

The episodes without combustion in situ are represented in sector X-32 specifically in the sublevel CE15a before c. 5250–5010 cal BC and in sector W-31 in sublevel of CE13, dated c. 5250–4960 cal BC. They are characterized by the presence of uncompacted, dispersed organic waste of plant origin and by the abundance of sheep/goat excrements, especially in the sublevel CE13. The silica phytoliths in the excrements show that the animals’ diet consisted mainly of monocotyledonous plants. The presence of rondels is indicative of grasses, which grow in humid and fresh environments (Koromila et al., 2018).

One of the surprising aspects is the small amount of residues of plant origin and the fact that no traces of combustion are observed, which is unusual in pen caves or rockshelters in our area of study, although similar levels of unburned stabling also appear in the Bronze Age in the area of the Ramon Crater and Ha Roa rockshelter sites (Negev Desert, Israel) (Macphail & Goldberg, 2018). Our interpretation is that either these sectors correspond to marginal areas of the stables and the fire would not reach them, or the pen was used sporadically or only for overnight stays, which would require less fodder and bedding, and therefore, less waste would be generated, and there would be no need to burn. However, in the sublevel CE15a in both the X-32 and W-31 sectors, the waste does not appear to have been burned, which leads us to believe that the lack of combustion was intentional. It should be noted that in the use of sheep and goats, bedding is of great importance and is closely related to the exploitation and shepherding system (Sierra, 1967).

In summary, in Cova Colomera, during the Early Neolithic, mainly on level CE14 and possibly on the reworked sublevel CE12, there were episodes where the permanence of the cattle in the cave was represented both by traces of combustion and by important quantities of bedding and fodder. The permanence of cattle in the location is also corroborated by the fact that in both levels, the breeding of ovicaprines in situ has been documented in fauna studies (Oms et al., 2015); this is also evidence of the permanence, at least during the breeding months, probably at the end of winter and spring (Martín & Oms, 2021).

In contrast, in the CE15a and CE13 sublevels, the occupation was more eventual, without traces of combustion, in which the cavity would function as a place of passage or as a nocturnal pen. From the faunal study of the CE13 level, a shorter duration is also inferred (Martín & Oms, 2021).

In general, the excrements appear very well preserved without trampling traces, a feature that indicates that there has not been much animal transit; this suggests the possibility that the stabled herds were small.

5.2 Paleoenvironment

From the sequence analyzed of Cova Colomera, a series of phases can be seen, which are detailed below and that frame the environment and the landscape in the surrounding area of the cave:

1. Before c. 5250–5010 cal BC, sublevel CE15a: It was initially formed by a process of run-off and later by an episode of stabling. In the W-31 sector, it is mixed with some guano components and finally appears reworked by a slight reactivation of the sheetwash type karst system.

2. c. 5250–5010 cal BC, level CE14 (sector X-32): An episode of stabling provides information on the vegetation around the cavity due to the good preservation of the bedding and/or fodder, together with the anthracological study, which indicates a domain of Quercus sp. deciduous and Buxus sempervirens, with the minor presence of Pinus sylvestris, Acer, and Juniperus (Oms et al., 2015). This suggests a mixed forest environment of conifers, oaks, and beeches with an understory of grasses and shrubs such as box, typical of a relatively humid environment. Furthermore, the almost absence of detrital deposition in the cavity at this stage leads us to hypothesize certain environmental stability (Bergadà et al., 2018b).

   One of the exceptional aspects of Cova Colomera is the degree of preservation of these residues, which is rare in the context of cavities. This good preservation is probably due to a combination of several factors. First, the location of the cave in a steep gorge, Congost de Montrebei, which would be subject to the microclimatic effects of updrafts as has been observed in other caves (Bergadà, Poch, & Cervelló, 2015), together with the circulation of air through the karst conduit that we were still able to observe during the archeological fieldwork, may contribute to the maintenance of the dry conditions in the cavity. Also, the practical absence of biological activity means that the identified microstratigraphic units and their components are undisturbed (Courty et al., 1989). Another contributing factor is that the combustion probably took place shortly after use as a stable and thus reduced the activity of the microorganisms that degrade organic components.

3. c. 5250–4960 cal BC: The sequence continues only in sector W-31. There is a slight reactivation of low-energy water toward the top of the CE13 level, characterized by a detrital deposition of sandy silt with a subsequent episode of unburned stabling.

4. c. 5060–4780 cal BC: There is an episode of stabling, sublevel CE12, with evidence of combustion, but it has been reworked by detrital deposition that caused some mass displacement that prevents that episode from being characterized in situ.

To sum up, the environmental conditions recorded during the Late Cardial Neolithic period in Cova Colomera would be those typical of a stable environment, probably a stage of biostasy, which would favor a landscape with vegetation coverage, with some small local detrital sedimentary episodes located mainly in the W-31 sector of the cavity as a result of slight reactivations of the karst system itself.