Abstract—: Basal horizons of sedimentary formations in the Stoilensky opencast mine (Stary Oskol, Belgorod Region) are comprehensively studied for the first time. In paleodepressions at the top of the weathering crust developed over Precambrian metasandstones and metashales, Devonian (Lower Frasnian) sediments are found fragmentarily. The paleodepressions are predominantly filled with Lower Jurassic (Pliensbachian–Toarcian) and Middle Jurassic (Bajocian–Callovian) deposits dated based on fossils. The work provides a detailed description of three representative sections located in different parts of the opencast mine. Several levels of paleosols were identified. Microphytofossils, macroplant remains, and fossil fish fragments were studied. © 2025 Elsevier B.V., All rights reserved.