Research Article| October 01, 1949 WISSAHICKON SCHIST AT PHILADELPHIA, PENNSYLVANIA JUDITH WEISS JUDITH WEISS 328 17th ST., N.E., WASHINGTON, D. C. Search for other works by this author on: GSW Google Scholar Author and Article Information JUDITH WEISS 328 17th ST., N.E., WASHINGTON, D. C. Publisher: Geological Society of America Received: 23 Nov 1948 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Copyright © 1949, The Geological Society of America, Inc. Copyright is not claimed on any material prepared by U.S. government employees within the scope of their employment. GSA Bulletin (1949) 60 (10): 1689–1726. https://doi.org/10.1130/0016-7606(1949)60[1689:WSAPP]2.0.CO;2 Article history Received: 23 Nov 1948 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation JUDITH WEISS; WISSAHICKON SCHIST AT PHILADELPHIA, PENNSYLVANIA. GSA Bulletin 1949;; 60 (10): 1689–1726. doi: https://doi.org/10.1130/0016-7606(1949)60[1689:WSAPP]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 SocietyGSA Bulletin Search Advanced Search Abstract The Wissahickon schist of the region in and near Philadelphia originally was a sediment made up of sandy, shaly, and arkosic layers of varying thickness and composition. These sediments have been completely recrystallized and highly deformed during: regional metamorphism; however, the original compositional banding has been retained. The presence of the metamorphic index minerals, garnet, staurolite, kyanite, and sillimanite, in definite zonal arrangement, indicates that the regional metamorphism increased in intensity from northwest to southeast. The rocks of the area belong to the amphibolite and epidote-amphibolite facies.Granitization along the southwestern border of the area has altered the schist. Intrusive basic igneous rocks in the southern and eastern part of the area also show some granitization. Apart from the granitized rocks the chemical composition of the schist has not been changed appreciably, and the metamorphism may be considered as isochemical.The structure of the rocks is believed to be that of an abnormal synclinorium produced by compression. No explanation is offered for the coincidence of the northern limb of the synclinorium with the garnet and staurolite zones, the center with the kyanite zone, and the southern limb with the sillimanite zone. The northern limb of the synclinorium and the zones of regional metamorphism are truncated by faults. 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.