DARIAL  , a

gorge in the Caucasus, at the east foot of Mt . Kasbek, pierced by the river Terek for a distance of 8 m. between vertical walls of rock (5900 ft.) . It is mentioned in the Georgian annals under the names of Ralani, Dargani, Darialani; the Persians and Arabs knew it as the Gate of the Alans; Strabo calls it Porta Caucasica and Porta Cumana; Ptolemy, Feria Sarmatica; it was sometimes known as Portae Caspiae (a name bestowed also on the " gate " or pass beside the Caspian at Derbent); and the Tatars call it Darioly . Being the only avail-able passage across the Caucasus, it has been fortified since a remote period—at least since 150 B.C . In Russian poetry it has been immortalized by Lermontov . The present Russian fort, Darial, which guards this section of the Georgian military road, is at the northern issue of the gorge, at an altitude of 4746 ft .