The Yunes Formation occurs in central Puerto Rico and consists of quartz-bearing vitric and crystal vitric tuff, volcanic sandstone, and siltstone with some volcanic breccia, conglomerate, calcarenite, and lava. Maximum estimated thickness is 3000 meters. The Yunes is of late Paleocene to middle Eocene age.
Source: GNU records (USGS DDS-6; Reston GNULEX).
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