Kurgan Essentuksky 1 is located on the northern outskirts of Essentuki, the city in Stavropol region, between private houses on Atamanskaya Street (44° 03′57.0″ N, 42°54′09.0″ E) (Figs 1a–1c)
Essentuki is a resort town situated in the southern part of the Stavropol region, at the northern spurs of the Main Caucasian ridge, 80 km from Mount Elbrus, on the foothills of the Skalistyi Ridge at 600–640 m a.s.l. The terrain is a hilly treeless plain, cut by small gullies along the river valleys. The studied kurgan is allocated to the interfluve between the Kuma and the Podkumok rivers; it may also occupy the high second or third terrace of the Podkumok River. It is difficult to specify the exact geomorphic position because of the continuous urban development and changes in the original topography of the area. The climate is of the continental mountainous steppe type. The mean July temperature is +27.4° C, the maximum temperature reaches +37° C. The mean annual precipitation is 530–540 mm with a maximum in spring and early summer. The study area is characterized by a large number of sunny days (on average, 280 days per year). Zonal soils are ordinary chernozems on loesslike calcareous loams and clays (Calcic Chernozems (Loamic, Pachic)). The natural vegetation of the foothills is represented by oak and hornbeam forest patches alternating with meadow steppes; at higher elevations (800–1100 m a.s.l.) this forest-steppe vegetation is replaced by broadleaved (beech, oak, hornbeam)
forests. In the vicinity of the kurgan, there are agricultural and residential lands. Land plot immediately near the kurgan was given to private ownership and was abandoned. It has not been cultivated since
1991–1992. Thus, the area, where the background surface soil was studied, had been under long-term fallow for more than 25 years by the time of our work.
The study of the kurgan was begun with a morphological description of its structure. The kurgan was heavily cut from the southern sides (during the construction of the road along Atamanskaya Street) and the eastern sides (during land surveying and erection of private property fences). There was less disturbances in the north, but the entire periphery of the kurgan, with the exception of a small area in its western part, was not available for research.
The kurgan was built on a very gentle slope with gradient with 1°. In the kurgan, archaeologists identified six earthen and three stone (two different crepe and cromlech) constructions, which, due to disturbance of the kurgan were not completely seen on the faces of the central edge, but were clearly traced on the side edges. Four earthen and two stone constructions were preserved in the central cleaning wall of the kurgan, which were studied during paleopedological analysis and are shown schematically in Fig. d and partially in Fig. e.
Initially, during the building of the first earthen construction, the central burial was contoured by two low, latitudinally oriented banks made of brownish-yellow material taken from the deep horizons of the pit of the main burial. Then between these banks laid out adobe layers of darker humus material and more yellow, which alternated with each other. The layers had a bowl-shaped deflection; in addition to the fine earth, the layers included fine stone crumb from 3-4 mm to 1-2 cm in size, confined more to the dark layers than to the yellow ones. The length of the layers upward of the kurgan gradually decreased, and alternating layers in the cleaning wall formed an almost regular pyramid or cone (Fig. e, constructions 2, 3). Due to the fact that the center of the mound from the very top and up to the main burial was disturbed by subsidence after collapse of the burial cover and a later predatory pit, the upper part of the first earthen construction was not clearly visible (Fig. d). The pyramidal shape of the first earthen construction was more likely to be guessed than was visible. In addition, the center was shifted to the north due to the fact that a predatory pit cut through the southern part of the first and second earthen construction.
The second earthen construction was made in the same way as the first - the banks along the outer border and between them alternating dark and yellow layers with a bowl-shaped deflection, forming a pyramid. In this and in all subsequent cases, the yellow soil for the banks was no longer taken from the pit of the main burial, but from the territory adjacent to the kurgan. The second pyramid was visible much more clearly, both on the southern (Fig. E, structure 2) and on the northern sides of the western face of the central edge, since it went beyond the predatory pit. In the first and second constructions, the very first layer, lying on the burial and buried soil, consisted of gley material with a characteristic bluish-bluish color and many ocher spots.
The third and fourth earthen constructions also had small banks at the base of their outer contour, but inside the third structure there were noticeable differences in the structure of the layers on the western and eastern facets of the edge. In the section of the northern half of the eastern facet of the central edge, the alternating layers of dark and yellow materials that were traced on the western face were replaced by packs of dissimilar material, inside the packs having a slope according to the slope of the barrow construction. The packs were separated from each other by clear horizontal thin interlayers. In the third construction, 5–6 such packs can be traced from the north side of the eastern face of the central edge (Fig. e, structure 3). In the fourth earthen construction, again, the dark and yellow layers alternate, the bedding of the interlayers was subhorizontal, the intensification of the carbonization of the material of which this structure is made is clearly expressed (Fig. e, structure 4). In the third and fourth constructions, small stones in the dark layers were significantly smaller or absent.
The first stone construction - cromlech - consisted of stone slabs measuring 1.2 (1.5) × 0.6 (0.8) m in size, placed at the ends, tightly to one another, along the perimeter of the base of the entire kurgan structure. The stones of the second (early) and third (late) stone constructions lay in a homogeneous pale-gray carbonized material, which was supposedly used as cement, stones were fixed in it or him. No layers can be traced in this material; it is homogeneous. The second and third stone constructions are visible only on the northern side of the kurgan, since in its southern part stones go under the road along the street and were partially used in the construction of this road. When viewing the mound from above (Fig. c), the bilayer of the stone laying is clearly visible (two successive crepes are distinguished) from its northern side: the lower part is the second stone construction (crepe I) and the upper is the third stone construction (crepe II). The stone material in stone constructions, both large slabs and relatively small stones, is beshtownite (alkaline pyroxene-amphibole trachyliparite) - a rock that got its name from Mount Beshtau and was mined by ancient builders, apparently on talus from Sheludivaya Mountain ( 6 km to the north – east in a straight line or 8 km along the roads from the kurgan), or, possibly, from Mount Beshtau itself (about 9 km to the north – east from the kurgan in a straight line and a bit more on roads). In addition, crepe II (the third stone construction) recorded the use of individual river pebbles and cobblestones.
The relative narrowness of the chronological period of time (several decades) that the ancient builders needed to erect the kurgan, in addition to the radiocarbon dates for the first and third earthen constructions, is indicated by a number of indirect signs recorded during excavations, and some speculative conclusions. Among them, a clearly visible unified architectural plan for the construction of the kurgan, which was erected over a single grave (central burial); common building techniques used in the construction of the various components of the kurgan structures, in some cases their close relationship, and at the same time noticeable differences in different sections of the same structure, which can be explained by small temporary (probably seasonal) interruptions in construction; identical ceramics found in all constructions of the kurgan and beyond on the ritual / memorial site, as well as the presence of many others, including large Maykop kurgans nearby. In addition, all the earthen constructions of the Essentuksky 1 kurgan, with the exception of the first, broken by robbers, had clear and sharp boundaries on the faces of the central edge, which would not have happened if the kurgan earthen constructions were built with significant temporary interruptions. For example, such breaks were clearly diagnosed in the field and subsequently confirmed by laboratory studies on the initial soils formed on the the Bolshoi Ipatovsky kurgan, previously studied in the Stavropol region.
Early Bronze Age, the Maykop culture, second quarter of the 4th millennium BC.
According to radiocarbon dating performed by AMS method in the laboratory of the Kurt Engelhorn Center for Archeometry in Mannheim (Germany), intervals 3653–3522 and 3637–3521 cal BC were obtained for samples from the first and third earthen constructions of the kurgan, respectively .
The pedo-chrono-sequence, buried under different constructions in the large kurgan Essentuksky 1 in Ciscaucasia, built by representatives of the Maikop culture in the second quarter of the 4th millennium BC, was studied. According to archaeological data, the mound was built for several decades. Paleosols buried under the kurgan have the following horizonation: Аhkb (down to 45 cm), АhВkb (80 cm), В1kb (120 cm), В2kb (150 cm), and ВСkb–Сkb (200 cm). All the soil profiles effervesced with HCL from the surface. The soils of the first three sections are classified as deep light clayey ordinary chernozems on carbonate loesslike clay (Calcic Chernozems (Loamic, Pachic)), whereas the soil of the fourth pit can be classified as a light clayey southern chernozem on carbonate loesslike clays (Haplic Calcisol) (Loamic). During the time of the kurgan construction, the morphological appearance and physicochemical properties of soils changed, namely, there was a decrease in the color saturation of the humus profile and organic carbon content, an increase in the content of gypsum, carbonate carbonates, their accumulation zone moved upward along the profile, transformation of the carbonate pedofeatures. The most “arid” image has the soil buried last in the studied chronological order: the humus horizon is the lightest and the organic carbon content in it is lowest, the profile is most enriched in carbonates, which is manifested both at the macro and micro levels of observation, the highest content of exchangeable sodium and magnesium in the composition of exchange bases, a decrease in the magnitude of the magnetic susceptibility and maximum values of the gypsum content in the second meter of the profile.
The profile of the surface soil is identical to the buried paleosols in terms of the set of horizons and their thickness, except for the upper former arable horizon. Nowadays its upper 10-cm layer represents a sod horizon with dense root system, and its lower boundary is not clearly seen at a depth of 20–25 cm. Carbonate coatings on ped faces and pseudomycelium appear at a depth of 60 cm; the horizon with well-pronounced carbonate pseudomycelium extends to the depth of 120 cm. Below, the soil contains beloglazka nodules with indistinct boundaries, gypsum veins were not noticeable. The modern soil similar to the paleosols in the first three pits, is classified as a deep light clayey ordinary chernozem on carbonate loesslike clay (Calcic Chernozems (Loamic, Pachic)).
The short-term pedochronosequence of the Essentuksky 1 kurgan is a unique object for studying both the age of the structure (Maikop culture, more than 5500 BP), under which the studied soils are buried, and the estimated speed of construction of the kurgan, several decades, which allows us to determine the time scale of the evolution of the properties of the studied soils.
From the beginning to the end of the construction of the kurgan, During the construction of the kurgan, a change in the soil subtype took place: typical thick chernozems on loesslike carbonate clays (Haplic Chernozems (Loamic, Pachic)) evolved to ordinary thick chernozems (Calcic Chernozems (Loamic)).
Based on paleobotanical data, it can be noted that during the construction of the kurgan, there was a decrease in the area of forests and an increase in the share of grassy vegetation, its stagnation and xerophytization, which is associated with a decrease in moisture and heat supply in the territory. The differences are not very large, due to the short interval between soil burials.
The studied object reflects the direction of climate change towards aridity and an increase in heat supply in the early Maykop time, in the second quarter of the 4th millennium BC.
Сверчкова А.Э., Хохлова О.С., Калмыков А.А. Изменчивость свойств черноземов и условий палеосреды в Предкавказье в середине IV тыс. до н. э. (на основе изучения большого кургана Eссентукский. Почвоведение, 2020. №12. С. 1436-1450. DOI: 10.31857/S0032180X20120126
Sverchkova A.E., Khokhlova O.S., Kalmykov A.A. Variations in the Properties of Chernozems and Paleoenvironmental Conditions in the North Caucasus in the 4th Millennium BC according to the Results of the Study of Essentuksky 1 Kurgan. Eurasian Soil Science, 2020, Vol. 53, No. 12, pp. 1687–1700. DOI: 10.1134/S1064229320120121