The loess quarries of the twentieth century in Khmelnytskyi city area: contemporary morphology and geomorphological processes
Authors: Koltun Oksana 
Published: November 2019

In contrast to the scrutiny to loess as deposits on one side and to open mines of minerals in rocks on the other side, loess quarries as landforms and as arena of contemporary human caused geomophologic processes became the object of study just recently. The article discusses features of 17 loess quarries in the Khmelnytskyi city area. They developed brick-tile raw materials in the twentieth century. Ten quarries locate on the banks of the Samets River and on its tributaries. Seven of them locate on the left bank of the Southern Bug River and on the banks and tributaries of Ploska River. The general morphological analysis, the revising of the XXth century topographic maps and the city plans, the geotechnical data analysis are the main methods, presented in research. Khmelnytskyi city territory is a set of Podolian Upland in east part, shaped in two bedrock layers of Upper Cretaceous (limestone) and Lower Neogene (clay), covered by Quaternary deposits and sediments, including loess-soils-series. The thickness of last reaches up to 30 m. Analysis of the geotechnical engineering data within highthickness loess-soil-series areas shows that the groundwater level location is from 3,5 to 20 m and deeper, most often is 7–11 m. These geological and hydrogeological features became the reason to the placement of loess open pits here. The depth of excavation in the mid-twentieth century was 2,5–21,5 m, area of 0,2–3,0 hectares. Subsequently, the area of three largest quarries increased to 10–30 hectares. In 2016 the highest height of ledges of former quarries is only 12 m. The dominant forms of initial stage contour were partially closed circular or oval; diameter (as well as the length of big axis or ledge) was 70–250 m. Except one working quarry at Pivnichnyi district the remaining 16 are closed since 1990 at the latest. The field research of ten quarries in April–June 2016 results in a leveling of morphological features, especially into low-rise buildings areas (seven out of ten). Terraces and benches or retaining walls are typical slope modification in four quarries (partly), flattering and slope stabilization using vegetation (trees) occur in nine quarries (also partly). Only those that use the territory for outdoor sports facilities and to a lesser extent – industrial zones have clearly expressed but still changed ledges. But less modified quarries have the landslides on the slopes of the height of 5 m and more, mainly south-faced. The types of landslides include earthflow, rotational and transitional landslides, spreads (rare) and one case of the anthropogenic debris flow in 1997 (caused by leakage and seepage of water from the water tower on the ridge of former quarry scarp, accompanied by other landslides types). In five quarries relatively old (20–40 years) and recent (up to week) landslides are detected, the biggest body has length of about 100 m. Slow earthflow was indicated by curved tree trunks in six quarries. The results of study of loess quarries of the twentieth century are similar to the earlier made findings about the morphology of loess quarries of the nineteenth century in Khmelnytskyi and geomorphological processes occurred on them. Key words: loess quarry, artificial terrain, terrain morphology, landslides, geomorphological processes, Khmelnytskyi City.