Knickzone propagation in the Black Hills and northern High Plains: A different perspective on the late Cenozoic exhumation of the Laramide Rocky Mountains

Research Article| June 01, 2001 Knickzone propagation in the Black Hills and northern High Plains: A different perspective on the late Cenozoic exhumation of the Laramide Rocky Mountains Brent J. Zaprowski; Brent J. Zaprowski 1Department of Earth and Environmental Sciences, Lehigh University, Bethlehem, Pennsylvania 18015, USA Search for other works by this author on: GSW Google Scholar Edward B. Evenson; Edward B. Evenson 1Department of Earth and Environmental Sciences, Lehigh University, Bethlehem, Pennsylvania 18015, USA Search for other works by this author on: GSW Google Scholar Frank J. Pazzaglia; Frank J. Pazzaglia 1Department of Earth and Environmental Sciences, Lehigh University, Bethlehem, Pennsylvania 18015, USA Search for other works by this author on: GSW Google Scholar Jack B. Epstein Jack B. Epstein 2U.S. Geological Survey, MS 926A, Reston, Virginia 20192, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Brent J. Zaprowski 1Department of Earth and Environmental Sciences, Lehigh University, Bethlehem, Pennsylvania 18015, USA Edward B. Evenson 1Department of Earth and Environmental Sciences, Lehigh University, Bethlehem, Pennsylvania 18015, USA Frank J. Pazzaglia 1Department of Earth and Environmental Sciences, Lehigh University, Bethlehem, Pennsylvania 18015, USA Jack B. Epstein 2U.S. Geological Survey, MS 926A, Reston, Virginia 20192, USA Publisher: Geological Society of America Received: 13 Nov 2000 Revision Received: 12 Feb 2001 Accepted: 26 Feb 2001 First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (2001) 29 (6): 547–550. https://doi.org/10.1130/0091-7613(2001)0292.0.CO;2 Article history Received: 13 Nov 2000 Revision Received: 12 Feb 2001 Accepted: 26 Feb 2001 First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Brent J. Zaprowski, Edward B. Evenson, Frank J. Pazzaglia, Jack B. Epstein; Knickzone propagation in the Black Hills and northern High Plains: A different perspective on the late Cenozoic exhumation of the Laramide Rocky Mountains. Geology 2001;; 29 (6): 547–550. doi: https://doi.org/10.1130/0091-7613(2001)0292.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Geomorphic research in the Black Hills and northern High Plains poses an intriguing hypothesis for the Cenozoic evolution of this salient of the Laramide Rockies. Most recently, geologists have appealed to late Cenozoic epeirogenic uplift or climate change to explain the post-Laramide unroofing of the Rockies. On the basis of field mapping and the interpretation of long-valley profiles, we conclude that the propagation of knickzones is the primary mechanism for exhumation in the Black Hills. Long profiles of major drainages show discrete breaks in the slope of the channel gradient that are not coincident with changes in rock type. We use the term knickzones to describe these features because their profiles are broadly convex over tens of kilometers. At and below the knickzone, the channel is incising into bedrock, abandoning a flood plain, and forming a terrace. Above the knickzone, the channel is much less incised, resulting in a broad valley bottom. Numerous examples of stream piracy are documented, and in each case, the capture is recorded in the same terrace level. These observations are consistent with migrating knickzones that have swept through Black Hills streams, rearranging drainages in their wake. We demonstrate there are two knickzone fronts associated with mapped terraces. Preliminary field evidence of soil development shows that these terraces are time transgressive in nature. Our data strongly suggest that knickzone propagation must be considered a viable mechanism driving late Cenozoic fluvial incision and exhumation of the northern High Plains and adjacent northern Rocky Mountains. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.