File:Geology (1907) (14774064244).jpg

Identifier: geology00cham (find matches)
Title: Geology
Year: 1907 (1900s)
Authors: Chamberlin, Thomas C. (Thomas Chrowder), 1843-1928 Salisbury, Rollin D., 1859- joint author
Subjects: Geology
Publisher: New York, H. Holt and co.
Contributing Library: Internet Archive
Digitizing Sponsor: Internet Archive

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cial faunas.—On the Atlantic coast there were, at the north, a series ofsubfaunas corresponding to the Ripley fauna at the south, and above these(New Jersey and Maryland), there were faunas not found at the south.1The earliest faunal group at the north embraced the sub-faunas of theMerchantville, Woodbury, Marshalltown, and Wenonah beds, and corre-sponded essentially with the fauna of the Matawan formation.2 In the Mer-chantville sub-fauna, Axinea mortoni, Idonearca antrosa, Trigonia eufaulensis-and Panopea decisa are abundant. In the Woodbury beds next above, most ofthese are rare, and Cyprimeria, Breviarca, Lucina cretacea, Cancellaria subalta,and others, rare or absent below, become the commonest species. In the Marshall,town beds, Trigonia, Cyprimeria, and Idonearca vulgaris are abundant, while 1 See Reports of Maryland and New Jersey. 2 Weller and Knapp, The Classification of the Upper Cretaceous Formations andFaunas of New Jersey, Jour. Geol. XIII, 1905, pp. 71-84. 1SS GEOLOGY
Text Appearing After Image:
Fig. 417.—Cretaceous Invertebrates (For explanation of figure see p. 189.) THE CRETACEOUS PERIOD. 189 the ponderous Gryphcea vesicularis and Exogyra ponderosa, with Ostrea larva ingreat abundance, are conspicuous faunal elements. In the Wenonah beds,the uppermost member of the group, there is a return of many of the speciesof the earliest subfauna, implying that the fluctuations in life were local. A more marked faunal change then ensued, corresponding approximatelyto the transition from the Matawan to the Monmouth, in which a new immi-grant element is introduced, characterized by Belemnitella americana andTerebratella plicata. There is at the same time a recurrence of the big oysters,Gryphcea vesicularis, Exogyra costata, and Ostrcea larva. Within the Monmouthformation there are also recurrences of other Matawan species. The above, in ageneral way, stand for the faunas of the lower portion of the series, south tothe Mississippi embayment, including the Eutaw and Ripley faunal group

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