Title: Bulletin of the Geological Society of America
Identifier: bulletinofgeolo221911geol (find matches)
Year: 1890 (1890s)
Authors: Geological Society of America
Subjects: Geology
Publisher: (New York : The Society)
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Biodiversity Heritage Library

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480 E. O. ULRICH REVISION OF THE PALEOZOIC SYSTEMS
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mouth of Illinois Eiver/^ probably pinches out or be- comes unrecognizable in the vicinity of Hannibal, Mis- souri. The facts in hand are explained as follows: 1. The whole series repre- sents uninterrupted deposi- tion in and adjacent to an advancing shallow sea. 2. The Everton, with its basal layer of sand^ represents deposition in embayments while the sea was still con- fined to areas south of Mis- souri. 3. The St. Peter sandstone is a well developed beach formed of wind-transported quartz grains from the north. 4. In the early part of ihU stage the beach seems to have gained on and possibly over- come the advance of the sea in northern Arkansas, but subsequently it was itself progressively drowned and its development pushed north- ward to some line beyond the present limits of the St. Peter. 5. Finally, the Joachim represents off-shore deposi- tion during the latter half of the time consumed in the tan- gential deposition of the St. Peter beach sands. ^^ Apparently this is the formation to which the name Folly limestone was applied by C. R. Keyes (Proc. Iowa Acad. Sci., vol. v, 1898, p. 61).

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