The Río Murta river follows a glacial valley cut into granitic rocks of the North Patagonian Batholith. The columnar-jointed lava flows include pillow lavas, lava tubes, and subglacial and sublacustral deposits. They have been considered to be of Holocene age due to lack of erosion, but recent studies suggest an age of 850,000-900,000 years ago for most flows, while at least some flows could be still Holocene in age.
