Gardner — Relation of the Late Tertiary Faunas. 305 



Art. XXI. — Relation of the Late Tertiary Faunas of 

 the Yorktown and Duplin Formations; by Julia A. 

 Gardner. 



Contributions to the geology and paleontology of the 

 Virginia and North Carolina Tertiaries have appeared from 

 time to time since the days of Maclnre and Say, but no mono- 

 graphic work was attempted until the recent cooperative study 

 of the coastal plain formations under the auspices of the United 

 States Geological Survey, and the Surveys of Virginia and 

 North Carolina. Reports upon the stratigraphy have already 

 been issued by the respective state surveys,* but those upon 

 the paleontology are not yet published. 



The following formational units have been recognized in the 

 Middle Atlantic Coastal Plain : 



Virginia North Carolina 



Pliocene Waccaraaw 



Yorktown Yorktown, Duplin 



Miocene St. Mary's St. Mary's 



Calvert 



The Calvert and St. Mary's have been traced southward from 

 the Maryland region, where they were first differentiated and 

 are best developed. The type locality of the Yorktown, how- 

 ever, is at Yorktown in southeastern Virginia, that of the 

 Duplin at the Natural Well in the environs of Magnolia, 

 Duplin County, North Carolina, and that of the "Waccamaw 

 along the Waccamaw River in northeastern South Carolina. 

 The present areal extent of the three last mentioned is shown 

 in fig. 1. 



All of the formations contain prolific molluscan faunas and 

 very extensive collections have been available for study. f The 

 shells are exceptionally well preserved, so perfectly, indeed, 

 that many individuals still retain the enamel and traces of the 

 color pattern. The fauna is exceedingly interesting, not only 

 because of its diversity and the remarkable development of 

 certain groups, but especially because it so fully confirms the 

 opinion of Shaler,;}; Glenn, § Dall,| and others, that the vicinity 

 of the Hatteras axis was, in Tertiary times, as it is in Recent, 

 a critical area in the distribution of the marine life, and that, 



*N. C. Geol. Surv., vol. iii, 1912. Va. Geol. Surv., Bull, iv, 1912. 

 f Collected by Steplienson, Miller, Twitchell, Bassler, and Berry. 

 jShaler, 1871, Proc. Boston Soc. Nat. Hist., vol. xiv, pp. 110-123. 

 § Glenn, 1899, American Geologist, vol. xxiii, pp. 375-379. 

 || Dall, 1903, Trans. Wagner Free Inst. Sci., Philadelphia, vol. iii, pt. vi, 

 p. 1598. 



