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The Miyara Formation is a S–SW-dipping succession of conglomerate, sandstone, shale, and limestone rocks deposited along the coast of Ishigaki Island.<ref name=":9" /> A large variety of marine fossils—e.g., calcareous algae, foraminifera, corals, [[Echinoderm|echinoderms]], [[Bryozoa|bryozoans]], and [[Gastropoda|gastropods]]— have been preserved in the limestones, and [[Mollusca|molluscs]] were also found in the conglomerate.<ref name=":9" /> Foraminifera and calcareous algae suggest a late Eocene age.<ref name=":9" />
The Nosoko Formation is a 300m thick sequence of tuff, volcanic sandstone and breccia, and lavas with dykes, sills, and other small intrusions.<ref name=":9" /> This formation is widely exposed at the Nosoko peninsula in northern Ishigaki Island.<ref name=":9" /> It also lies conformably above the Miyara Formation.<ref name=":21" /> [[Paleomagnetism|Paleomagnetic]] data of the Nosoko Formation indicate a mean deflection of the magnetic direction at about 30˚ clockwise away from the expected pole.<ref name=":17">Miki, M. (1995). Two‐phase opening model for the Okinawa Trough inferred from paleomagnetic study of the Ryukyu arc. ''Journal of Geophysical Research: Solid Earth, 100''(B5), 8169–8184. https://doi.org/10.1029/95JB00034</ref> This data, coupled with [[Radiometric dating|radiometric]] ages, suggest that Southern Ryukyu might have rotated about 25˚ with respect to the Asian continent in the Miocene at 6-10 Ma.<ref name=":17" />
===Yaeyama Group===
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