The Duplin Formation is composed of unconsolidated sand and mud representing Late Pliocene (3 to 3.2 million years) brackish to open marine sediments. It has a limited surface exposure, ranging from Southeastern North Carolina to Northeastern South Carolina. The major macrofossil component is mollusks with some crustacean, echinoderm and vertebrate representatives. Biostratigraphically, its fauna is equivalent to Zone 2 Yorktown to the north, the Jackson Bluff Formation in the Florida Panhandle and the Pinecrest Member of the Tamiami Formation in South Florida. Uplift in the Neuse River region during the Pliocene separated the Duplin and Yorktown faunas and as a result, the Duplin contains many warmer water species found in Florida but absent in Virginia.

In late 2009 and 2010, I had the opportunity to collect two separate Duplin localities in Bladen County, North Carolina which are now sadly off-limits by land owner request. The first site visited, my location number 1007, was a winding creek which cut through high hills for a mile or so. Along the way we found many logs which looked like weathered recent trees but were actually petrified and produced a characteristic “clink” when tapped with a pick (fig. 1). Fossil shells were found as float and by digging in a 40 foot bluff and in a side feeder creek.

Figure 1. Petrified logs of undetermined age found along creek loc. 1007

The second site (Loc. 1006) was a different creek and was limited to about 15-20 feet of exposure along the stream banks. Further downstream the Duplin sat directly on Cretaceous strata (probably Black Creek Formation) containing soft wood. Collecting the Duplin here consisted of digging in the creek banks and screening with ¼”-mesh. This locality produced gorgeous shells some which are picture below (fig. 2).

Figure 2. Warm water gastropods from locality 1006. Bladen County, North Carolina. a) Terebraspira acuta (Emmons, 1858); b )Pleioptygma carolinensis (Conrad, 1840); c) Scaphella trenholmii (Tuomey & Holmes, 1856); d) Sconsia hodgii (Conrad, 1841); e) Architechtonica nobilis Roding, 1798.

Several shells found were not listed by Campbell (1993) as Duplin or as a valid species, but which I named based upon the following criteria:

1. Nodipecten nodosus (Linne, 1758). (fig. 3). Campbell does not list a Nodipecten in the Duplin. Identification is based upon figures from other references and is found in the contemporaneous Pinecrest of South Florida.

2. Fulguropsis carolinensis (Tuomey & Holmes, 1856). (fig. 4). Petuch raised most of the subgenera in Busyconidae to genus level, however Campbell recognizes only Busycon. This species is not listed in Campbell as he might consider it a variation/synonym to Busycon excavatum Conrad, 1840. Specimens from loc. 1006 are nearly identical to that shown in Petuch’s Atlas, pg. 172 A. I could not use Buyscon as Campbell states that Busycon carolinensis Emmons, 1858 (Campbell, 1993 pg 82 no. 397) is a synonym for Busycon canaliferum Conrad 1862, a completely different looking shell and subgenus. All the shells of this species collected from loc. 1006 had the wide and deep spire suture. A single specimen from loc. 1007 had a suture more like B. excavatum and was identified as such although it was immature and not complete.

3. Busycon tritonis Conrad, 1863. (fig. 5). Campbell lists B. tritonis as a synonym of Busycon maximum filosum Conrad, 1862 which has fluted costae and a swollen ridge at the base of the canal. A comrade collected a filosum at loc. 1006 which looks identical to that figured in Petuch’s Atlas, pg. 162 E. The shell I collected at loc. 1007 had none of those features and looked closer to Busycon maximum maximum (Conrad, 1839) with the exception of the shoulder spines.

Figure 3. Nodipecten nodosus (Linne, 1758). Locality 1006, Bladen County, North Carolina.

Figure 4. Comparison of spiral suture. Left: Fulguropsis carolinensis (Tuomey & Holmes, 1856). Locality 1006, Bladen County, North Carolina. Right: Busycon (Fulguropsis) excavatum Conrad, 1840, Pinecrest Member of the Tamiami Formation, Locality 92, Sarasota County, Florida.

Figure 5. Comparison of Busycon tritonis Conrad, 1863, Duplin Formation, Locality 1006 (left) and Busycon maximum maximum (Conrad, 1839), Rushmere Member of the Yorktown Formation, Locality 923, Petersburg, Virginia.

As I mentioned in my previous post, I also deviate from Campbell with cones. At loc. 1006 I found several examples of Conus delessertii Recluz, 1843 (fig. 6) previously called Conus presozoni Olsson and Petit, 1964 but made a synonym by Hendricks (2009). Also of note were Cretaceous shark teeth Squalicorax kaupi (Agassiz, 1843) which were redeposited in the Duplin. Attached are lists of the mollusks that I found at both localities.

Figure 6. Conus delessertii Recluz, 1843 Left:Duplin Formation, Loc. 1006, Bladen County, North Carolina; Right: Recent Gulf of Mexico, Florida.

Loc 1006 Bivalvia Duplin Formation.pdf

Loc 1006 Gastropoda Duplin Formation.pdf

Loc 1007 Mollusca Duplin Formation.pdf