The Măcin Mountains are one of the oldest in Romania, being formed in the second part of the Paleozoic, in the Carboniferous and Permian, during the Hercynian orogeny. The predominant rock is granite. Erosion (caused by the difference of temperature) has created steep slopes, with the aspect of ruins.
They are divided in Culmea Măcinului (the southern part) and Culmea Pricopanului (the northern part). The highest peak is Țuțuiatu (also called Greci) which has a height of 467 meters. Other important peaks are Priopcea Hill (410 m) and Muntele lui Iacob ("Mountain" of Iacob – 341 m).