The folded formations developed in the northwestern part of the Turgai Trough appear on the surface only in the valleys of the Tobol River and its largest tributaries, where they were studied by Meglitsky and Antipov, A. A. Krasnopolsky, A. N. Geisler (1929), D. S. Steinberg (1929), A. P. Zotov (1935), A. G. Behr, G. A. Sokolov (1934), E. A. Ushakova (1932), K. I. Dvortsova (1937‑1940), F. N. Rukavishnikov (1938), A. P. Krotov (1943), E. I. Klevtsov (1946‑1947), N. N. Pikhtovnikova (1946), E. A. Mazina and other researchers. Huge areas of watersheds remained practically unexplored.