Erik P. Kvale, Allen W. Archer, Hollis R. Johnson; Daily, monthly, and yearly tidal cycles within laminated siltstones of the Mansfield Formation (Pennsylvanian) of Indiana. Geology ; 17 (4): 365–368. doi: https://doi.org/10.1130/0091-7613(1989)017<0365:DMAYTC>2.3.CO;2
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Whetstones (laminated siltstones) within the Mansfield Formation of Orange County, Indiana, are Lower Pennsylvanian (Morrowan) tidal deposits characterized by rhythmic laminations. Laminae thicknesses vary systematically in a vertical sequence and reflect tidal events of a mixed tidal regime. So complete is the record of tidal deposition that daily and monthly tidal cycles can be delineated. Neap-spring tides (related to the phases of the moon) and equatorial-tropical tides (related to the declination of the moon) are recognizable within the sequence.