Disequilibrium profile of the Potomac River near Washington, D.C. – A result of lowered base level or Quaternary tectonics along the Fall Line?

Research Article| October 01, 1981 Disequilibrium profile of the Potomac River near Washington, D.C. – A result of lowered base level or Quaternary tectonics along the Fall Line? John C. Reed, Jr. John C. Reed, Jr. 1U.S. Geological Survey, Federal Center, Denver, Colorado 80225 Search for other works by this author on: GSW Google Scholar Author and Article Information John C. Reed, Jr. 1U.S. Geological Survey, Federal Center, Denver, Colorado 80225 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1981) 9 (10): 445–450. https://doi.org/10.1130/0091-7613(1981)9<445:DPOTPR>2.0.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation John C. Reed; Disequilibrium profile of the Potomac River near Washington, D.C. – A result of lowered base level or Quaternary tectonics along the Fall Line?. Geology 1981;; 9 (10): 445–450. doi: https://doi.org/10.1130/0091-7613(1981)9<445:DPOTPR>2.0.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 Longitudinal profiles of major rivers in Maryland and Virginia are generally closely adjusted to the resistance of the rocks over which they flow, but they all show major discontinuities at or just above the Fall Line. The amount of discrepancy at the Fall Line between the actual profiles and the projection of the profiles of the upstream reaches increases from about 27 m at the James River to about 50 m at the Susquehanna River. At the Potomac River it is about 45 m. Detailed study of the terraces along the Potomac in the Piedmont above Washington, D.C., suggests that the discontinuity in longitudinal profile is the result of Quaternary downcutting in response to a lowered base level. Changes in base level during sea-level fluctuations in the Pleistocene must have been an important factor, but strong circumstantial evidence suggests that the discontinuities in river profiles may in part be due to differential uplift of the Piedmont with respect to the coastal plain along a zone of flexure or distributed faulting near the Fall Line. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.