Gjáin is a short gorge near the ruins of the old farm of Stöng in the valley of the Þjórsá River. Entrance is by a short path. The Red River cascades into the valley over two main waterfalls at the head of the gorge and races to meet the Foss River at Reykholt. The larger waterfall is Gjárfoss. Clear springs bubble into the gorge, with its rough cliffs and lush vegetation of mosses, grasses, willows, ling, angelica and birch, with vibrant bird life during the summer. Gjáin is one of the most peaceful and beautiful spots in the Þjórsá valley. Gjáin was largely formed thousands of years ago from running water, perhaps from the runoff of the forerunner of the Þjórsá River. Four lava flows (the Tungnaárhraun lava in the Veiðivötn area) have run through the gorge, competing with the erosive force of the water. The youngest, the Þjórsár Valley lava, swept over the area about 4000 years ago.