According to previous tests, come up to scientific findings that the valley emerged by tectonic influences. Crucial importance for today's form and relief structure had tectonic movements that occurred before the middle of Oligocene. At that period the ground came down between two splitting lines, one from the north (Osogovo) and another from the south (Plačkovica). In late Miocene and early Pliocene, the valley was flooded by freshwater lake, which along with other neighboring lakes created the Middle Vardar's Lake. The depth of this pliocene lake was over 500 meters.