It is a special geological reserve, of volcanic origin, with an area of 392 km2 (approximately 10 hectares), forming a cliff with boulders towards the Mureșului terrace and a smooth slope to the north. A strong and prolonged saddle connects it to the rest of the hills to the north, where it seems that the Mureș once flowed.
Three andesitic lava flows can be observed in the Uroiului hill. It can be clearly seen from the city of Simeria, and an ascent on it offers a wide panorama of the Mureșului Valley, and to the south, as far as the Streiului Valley.
Source: Parks and nature reserves from Romania, Gheorghe Mohan, Aurel Ardelean, Victor Bortaș ed. Victor B. Victor, 2006
