Saturday, August 14, 2010

Endemic to the "upland deposits" of the U.S. Mid-Atlantic Coastal Plain, the cemented nano-particle ferric oxyhydroxide materials described here appear to be harder than quartz and weld together and penetrate well-rounded orthoquartzite pebbles and cobbles, wherein the resultant patterns in sectioned rocks are demonstrably different from those attributable to liesegang.

This work is extensively described in the following reference, which is available from the author as a color-photography-laden paper reprint upon request at or can be downloaded as a low-quality pdf here.

“Fossil natural glasses composed of ferric oxyhydroxides: Impactites of the 35.5 million year old Chesapeake Bay crater”, D.L. Griscom, A. Akiyoshi, T. Homae, K. Kondo, C. Yamanaka, T. Ueno, M. Ikeya, M. Affatigato, A. Schue, Proc. of “Natural Glasses 4”, Lyon, FRANCE, August 2002. J. Non-Cryst. Solids 323 (2003) 7-26.

Below are presented the first page of this paper (including all but 5 lines of the abstract) followed by a down-selection of PowerPoint slides epitomizing the much larger petrological and materials-science data base that has been developed and the analyses thereof that ultimately led, among other things, to proposition of the interference-zone-shock-wave model of petrogenesis illustrated in the final slide.


Note in addition to the petrological and materials-science arguments raised above that the rocks of this study result from impact-generated shock waves, there are also strong geological arguments for the upland deposits of Maryland, Virginia, and the District of Columbia being ejecta from the Chesapeake Bay crater.