USGS Earth Science Photographic Archive digital files: hjk00500 and hjk0500a
The Canyon of Lodore cuts through an uplifted plateau, exposing strata of the Uinta Mountain Group (dense sandstone and quartzite of late Precambrian age, about 1 billion years old). Downstream the river canyon cuts through progressively younger strata including the Lodore Formation (Cambrian sandstone, about 525 to 505 million years old) and strata consisting of limestone, sandstone, and shale of late Paleozoic Age (about 350 to 250 million years old). The dinosaur-fossil bearing strata of Mesozoic age (250 to 65 million years old) crop out along the southern and western margins of this uplifted region and along the Yampa River (but not in the vicinity of Canyon of Lodore). The mountain ranges of the Rocky Mountain region (including the uplift of the Uinta Arch) occurred in multiple stages of Laramide Orogeny (roughly 70 to 20 million years ago), and uplift is still proceeding in the region. Younger sedimentary deposits derived from the surrounding Laramide uplifts cap many of the mesas and uplifted areas throughout the park region.
