“Sod blocks” in kurgan mounds: Historical and soil features of the technique of tumuli erection

Abstract

Tumuli (Kurgans) over Bronze Age, Early Iron Age, and Middle Age burials are a common attribute of the landscape across the entire steppe zone of Eurasia. For many years, the kurgan embankment was believed to be created from loose soil and underlying sediments. However, in recent years, during the excavation of kurgans, archaeologists began to understand that the mounds contain large blocks of undisturbed soil. These blocks are a type of brick, carved from the upper sodded layer of soil held together in blocks by plant roots.We suggest the term “sod blocks” for such soil blocks. The earliest kurgan mounds made from sod blocks date to the Early Bronze Age. Sod blocks are found in burials from the Middle Bronze Age, but after that, the tradition of sod brick architecture begins to fade. During the Scythian era, from the 7th to 4th centuries BC, sod blocks are widely used for making huge “King's” kurgans. During the Early Sarmatian culture, in the 3rd to 1st centuries BC, the sod blocks technique disappears, arising again in the Middle Sarmatian of the 1st century AD. We found that sod blocks are well distinguished in tumuli if the kurgan is built from Solonetz, a soil with a light grey upper AE horizon and a reddish-brown underlying Bt horizon. Due to sharp differences between the upper two soil horizons, we can distinguish the sod blocks in kurgan mounds. The growing number of kurgans with traces of sod blocks in the mounds allows one to suppose that this method of kurgan construction was much more widely used than previously thought. Taking into consideration that most of the mounds have not been made from soil-forming rock, but from the upper soil horizons, from which one can easily cut sod blocks, we assume that most of the kurgans were made from sod blocks. The use of sod blocks can significantly expand the range of possible architectural proposals for the creation of the kurgan mound and provide an opportunity for building vertical elements. The purpose of this article is to consider the emergence and development of this kurgan building tradition and to show the most interesting examples of burial mounds built from sod blocks. Another task is to establish, in terms of soil science, why in some burial mounds soil blocks are clearly visible but in other cases are not.