A Billion Years Are Missing From the Grand Canyon

Deep inside the Grand Canyon there's a line you can put your hand on. Below it, rock about 1.75 billion years old. Right on top, sandstone about 508 million years old. Between them, up to about 1.2 billion years of Earth's history are simply gone — and even the official page can't agree on how much of Earth's history that is. Here's what Powell saw in 1869, why scientists have spent years arguing over ice versus tectonics, and why the newest study from inside the canyon says the gap formed in more than one episode. Chapters 0:00 A line you can touch 1:33 The canyon on the postcards 3:26 1869: into the granite 5:08 The page that can't do the math 6:46 The sandstone that got younger 8:38 Snowball Earth 10:26 Before the ice 12:07 Not a single block 13:38 The Cambrian connection 15:09 The ice strikes back 17:01 Every clue, a different culprit 17:40 Uncovered twice 19:48 How old is the canyon? 21:41 The men who left 23:06 The verdict Main sources National Park Service. Missing Time at Grand Canyon National Park (updated January 30, 2024); Grand Canyon statistics and FAQ; Vishnu Basement Rocks; Layered Paleozoic Rocks. Powell, J.W. (1875). Exploration of the Colorado River of the West and Its Tributaries. Smithsonian Institution. Dutton, C.E. (1882). Tertiary History of the Grand Cañon District. U.S. Geological Survey. Karlstrom, K.E. & Timmons, J.M. (2012). Many unconformities make one "Great Unconformity". Karlstrom et al. (2018). Nature Geoscience 11:438-443. · Karlstrom et al. (2020). Geology 48(5):425-430. Keller et al. (2019). Neoproterozoic glacial origin of the Great Unconformity. PNAS 116(4):1136-1145. doi:10.1073/pnas.1804350116 Flowers et al. (2020). Diachronous development of Great Unconformities before Neoproterozoic Snowball Earth. PNAS 117(19):10172-10180. doi:10.1073/pnas.1913131117 Peak et al. (2021). Zircon (U-Th)/He thermochronology reveals pre-Great Unconformity paleotopography in the Grand Canyon region, USA. Geology 49(12):1462-1466. doi:10.1130/G49116.1 — Comment by Karlstrom et al. and Reply, Geology 50(3), 2022. Peters, S.E. & Gaines, R.R. (2012). Formation of the "Great Unconformity" as a trigger for the Cambrian explosion. Nature 484:363-366. doi:10.1038/nature10969 McDannell et al. (2022). Thermochronologic constraints on the origin of the Great Unconformity. PNAS 119:e2118682119. Courtney-Davies et al. (2024). Hematite U-Pb dating of Snowball Earth meltwater events. PNAS 121(47). doi:10.1073/pnas.2410759121 Thurston et al. (2024). Deep-time thermal history of the Great Unconformity in the Grand Canyon, USA. GSA Bulletin 136(11-12). doi:10.1130/B37358.1 Thurston et al. (2022). Geology 50(2):222. doi:10.1130/G48699.1 Wernicke, B. (2011). The California River and its role in carving Grand Canyon. GSA Bulletin 123(7-8):1288-1316. Flowers, R.M. & Farley, K.A. (2012). Apatite 4He/3He and (U-Th)/He evidence for an ancient Grand Canyon. Science 338:1616-1619. Karlstrom et al. (2014). Formation of the Grand Canyon 5 to 6 million years ago through integration of older palaeocanyons. Nature Geoscience. doi:10.1038/ngeo2065 Image and footage credits National Park Service (Grand Canyon B-roll), USGS, NARA and NSF: public domain. NASA/Goddard Space Flight Center Scientific Visualization Studio; NASA Earth Observatory and ISS imagery; animation courtesy NASA/JPL-Caltech. CC BY 2.0 (https://creativecommons.org/licenses/by/2.... Chris M Morris ("Unconformity in Grand Canyon"); James St. John (unconformity, Burgess Shale, trilobite, diamictite and dropstone photos); Grand Canyon National Park on Flickr (Vishnu Schist, Zoroaster Granite, Tapeats Sandstone, trilobites, inner gorge). CC BY 4.0 (https://creativecommons.org/licenses/by/4.... Grand Canyon National Park (Transept Canyon aerial). CC0: Hermann Luyken; GeoDIL. Maps: Natural Earth (public domain). Graphics: The Landmark Files. Original music generated for this channel. Narration uses a synthetic voice.