The Harang facies, a regional diachronic middle Miocene shale in Louisiana, has characteristics which can be interpreted as indications of deep-water or cold-water deposition. It occurs in a seaward-thickening subsurface wedge or dark-gray to brown or black marine shales and clays with interbedded sandstones, and with a distinctive foraminiferal biofacies. The biofacies is characterized by an abundant and diversified benthonic foraminiferal fauna including huge arenaceous forms, and a small percentage of planktonic Foraminifera. Globorotalia fohsi, G. mayeri, G. menardii, and other planktonic species are sinistrally coiled. The change from random to predominantly sinistral coiling coincides approximately with the inception of Harang deposition (± 12-14 m. y. ago). Th faunal assemblages indicate a muddy-water outer neritic to bathyal environment, and suggest a cool water mass. The apparent anomaly of a cold-water fauna in this stratigraphic position in this area might be explained by upwelling, paleogeographic changes, and/or significant Miocene refrigeration.

During the time span that includes Harang deposition, continental glaciation in Antarctica, cold-water invertebrate faunas, cool-climate floras, and other evidences of cool climate in many parts of the world indicate mid-Miocene refrigeration. Although some conflicting evidence also exists, we conclude that the distinctive characteristics of the Harang biofacies are related to a cool water mass which was part of a worldwide cooling phenomenon.

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