The Kasagh Gorge formed around the Kasagh River, which originates on the slopes of Mount Aragats and flows south through the Aragatsotn Province, passing near Aparan, Ashtarak, and Oshakan, until it empties into the Hrazdan River. In the upper part of the gorge, the depth reaches about 100 meters.
In one of the rock niches opened in the walls of the gorge, at an elevation of 1,738 meters above sea level and about 70 meters above the Kasagh River, is the rock shelter known as Geghamavan-1, with ancient rock carvings.
In another section of the gorge, about 2 km north of Ohanavan, on the left bank of the Kasagh Gorge, within a tuff cliff, is the rock-cut Church of St. Astvatsatsin, locally known as the "Red Monasteries" ("Karmir Vank"). On the walls of the Church of St. Astvatsatsin above, geometric ornaments in red and crosses carved in the 13th century have been preserved, which is also the source of the complex's popular name.
