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Interpretation of Aeromagnetic Anomalies Bearing on the Origin of Upper Chesapeake Bay and River Course Changes in the Central Atlantic Seaboard Region: Speculations

1974; Geological Society of America; Volume: 2; Issue: 2 Linguagem: Inglês

10.1130/0091-7613(1974)2 2.0.co;2

1943-2682

Michael Higgins, Isidore Zietz, George W. Fisher,

Geological Studies and Exploration

Research Article| February 01, 1974 Interpretation of Aeromagnetic Anomalies Bearing on the Origin of Upper Chesapeake Bay and River Course Changes in the Central Atlantic Seaboard Region: Speculations Michael W. Higgins; Michael W. Higgins 1U.S. Geological Survey, Beltsville, Maryland 20705 Search for other works by this author on: GSW Google Scholar Isidore Zietz; Isidore Zietz 2U.S. Geological Survey, Silver Spring, Maryland 20910 Search for other works by this author on: GSW Google Scholar George W. Fisher George W. Fisher 3Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, Maryland 21218 Search for other works by this author on: GSW Google Scholar Author and Article Information Michael W. Higgins 1U.S. Geological Survey, Beltsville, Maryland 20705 Isidore Zietz 2U.S. Geological Survey, Silver Spring, Maryland 20910 George W. Fisher 3Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, Maryland 21218 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1974) 2 (2): 73–76. https://doi.org/10.1130/0091-7613(1974)2 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 Michael W. Higgins, Isidore Zietz, George W. Fisher; Interpretation of Aeromagnetic Anomalies Bearing on the Origin of Upper Chesapeake Bay and River Course Changes in the Central Atlantic Seaboard Region: Speculations. Geology 1974;; 2 (2): 73–76. doi: https://doi.org/10.1130/0091-7613(1974)2 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 On an aeromagnetic map of the Chesapeake Bay area, the northeastern part of the bay coincides well with a deep, “flat” magnetic low, and the upper part of the Delmarva Peninsula east of the bay coincides with detailed magnetic highs; the two areas are separated by a steep, straight gradient that matches the eastern shore of the bay. On the basis of magnetic and geologic evidence, we interpret the Chesapeake Bay magnetic low as a buried Baltimore Gneiss dome, bounded on the southeast by a normal or reverse fault marked by the steep, straight gradient; mafic and ultramafic plutonic rocks probably underlie the southeast side of the fault zone. The flatness of the Chesapeake Bay magnetic low, as opposed to the detail of the anomalies on either side, however, suggests that an abnormal thickness of nonmagnetic sedimentary rocks also coincides with the low. This could reflect a buried Triassic basin or, more probably, a thickened section of Coastal Plain sedimentary rocks deposited in the fault-bounded basin. The present course of the upper part of Chesapeake Bay is probably inherited from the pre-Pleistocene course of the Susquehanna River, but the river's course may have been determined by the fault zone. Thus, this zone and similar en echelon fault zones along strike may explain the sudden change in course of major rivers in the central Atlantic Seaboard region. 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.