Pg. 241, 242 (fig. 1), 243. Duck Lake stage. Stage name, based on faunal assemblages occurring in sediments commonly referred to as "Middle" Miocene in subsurface of southeastern Louisiana. Applied to sediments occurring between top of BIGENERINA 2 zone and top of DISCORBIS B zone, where present, or top of ROBULUS CHAMBERAI zone. Generally, best foraminiferal markers for this stage are (descending) BIGENERINA (2) NODOSARIA, TEXTULARIA (W) STAPPERI, BIGENERINA HUMBLEI, CRISTELLARIA I, CIBICIDES CARSTENSI var. OPIMA, ROBULUS 43, and OPERCULLINOIDES. Name selected arbitrarily only because denoted fields demonstrate representative sections for each; nothing in way of principal producing members is implied. Clovelly and Napoleonville stages are proposed as replacements for "Lower" and "Upper" Miocene respectively.
Named from Duck Lake field, [9 mi northwest of Morgan City, in T. 14 and 15 S., R. 11 and 12 E., southern St. Martin Parish, southeastern LA].

Source: Publication; US geologic names lexicon (USGS Bull. 1200, p. 1056); supplemental information from LA State Geol. Survey (written commun., Mar. 2007).

Duck Lake stage of McLean (1957). Regards Duck Lake and other terminology applied to post-Anahuac strata in subsurface of south Louisiana as being of questionable validity.

Source: Louisiana State Geol. Survey (written commun., Mar. 2007).

Pg. 412-416. Duck Lake stage. Composed of all beds in the coastal province which can be demonstrated as being equivalent in age to strata in wells of the Duck Lake field, St. Martin Parish, Louisiana. Characterized by assemblage zone containing the following foraminiferal species or equivalents (citing Akers and Drooger, 1957, AAPG Bull., v. 41, no. 4, p. 658-768; McLean, 1957): OPERCULLINOIDES sp., ROBULUS sp. or AMPHISTEGINA sp., CIBICIDES CARSTENSI OPIMA, CRISTELLARIA sp., BIGENERINA HUMBLEI, TEXTULARIA STAPPERI, and BIGENERINA NODOSARIA DIRECTA or CIBICIDES CARSTENSI. Duck Lake stage of McLean (1957) has priority over Doering's (1958) Pleistocene Duck Lake formation, which he considers invalid.

Source: Publication; LA State Geol. Survey (written commun., Mar. 2007).

Duck Lake Stage of Murray (1961) can only be applied to strata in very narrow belts within the Gulf of Mexico due to problems presented by the temporal and spatial stratigraphic distribution of the characteristic benthonic neritic species. Author proposes his own subdivisions of the Miocene (divisions J to A, ascending), based on established biostratigraphic (benthic forams) correlations of regional transgressive marine units. Duck Lake Stage of Murray (1961) = (ascending) divisions G through C of author (OPERCULINOIDES zone to top of BIGENERINA DIRECTA zone).

Source: Publication; LA State Geol. Survey (written commun., Mar. 2007).

Notes that the Harange assemblage appears to be approximately equivalent to the Duck Lake Stage of McLean (1957) as described by Murray (1961) and lies at the approximate position of the middle Miocene-upper Miocene boundary.

Source: Louisiana State Geol. Survey (written commun., Mar. 2007).

In some reports discussing Miocene sediments in the subsurface of southern Louisiana, the names Clovelly Formation, Duck Lake Formation (a name applied by Doering, 1958, to a Pleistocene subsurface unit in same area) and Napoleonville Formation have been misapplied to the biostratigraphically-defined Clovelly Stage, Duck Lake Stage, and Napoleonville Stage of McLean (1957).

Source: Louisiana State Geol. Survey (written commun., Mar. 2007).