%LRORJLFDO =RQDWLRQ RQ D 5RFN\6KRUH %RXOGHU 'HSRVLW 8SSHU 3OHLVWRFHQH %DKｯD 6DQ $QWRQLR %DMD &DOLIRUQLD 6XU 0H[LFR $XWKRUV 0DUNHV ( -RKQVRQ DQG -RUJH /HGHVPD9｣]TXH] 6RXUFH 3$/$,26 9RO 1R 'HF SS 3XEOLVKHG E\ SEPM Society for Sedimentary Geology 6WDEOH 85/ http://www.jstor.org/stable/3515314 . $FFHVVHG Your use of the JSTOR archive indicates your acceptance of JSTOR's Terms and Conditions of Use, available at . http://www.jstor.org/page/info/about/policies/terms.jsp. JSTOR's Terms and Conditions of Use provides, in part, that unless you have obtained prior permission, you may not download an entire issue of a journal or multiple copies of articles, and you may use content in the JSTOR archive only for your personal, non-commercial use. Please contact the publisher regarding any further use of this work. Publisher contact information may be obtained at . http://www.jstor.org/action/showPublisher?publisherCode=sepm. . Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printed page of such transmission. JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. SEPM Society for Sedimentary Geology is collaborating with JSTOR to digitize, preserve and extend access to PALAIOS. http://www.jstor.org