The Calvert Formation, deposited in a shallow sea during the late Oligocene and early to middle Miocene (15-27 million years ago), contains a very rich fossil microflora, both in terms of number of specimens and number of species. Most abundant are pollen of oak, pine, and hickory, but exotic taxa (those that no longer occur in Delaware) are present in all samples of this formation. They include pollen of Engelhardia type, Manilkara, Planera (water elm), Alangium(?), and palms. All of these exotics are genera of subtropical or tropical regions, some occurring now in Central America, Florida, and east Asia. The climate during the deposition of the Calvert Formation was probably subtropical and moist.
Borehole Oh25-02, located about 3 miles southwest of Lewes, Delaware, ends at a total depth of 1,337 ft in a mid-Oligocene glauconitic silt unit. It penetrated 317 ft of glauconitic sands and silts between the base of the Calvert Formation at a depth of 1,020 ft and total depth. A hiatus at 1,218 ft separates an outer neritic lower Miocene interval (Globorotalia kugleri Zone) above it from a deep upper bathyal mid-Oligocene (G. opima opima Zone) section below; the lower section is characterized by abundant large uvigerinid benthic foraminiferal species representing the transition from Uvigerina tumeyensis to Tiptonina nodifera. Similar uvigerinid assemblages identify the mid-Oligocene unit in boreholes near Bridgeville and Milford, Delaware; Cape May, New Jersey; and Ocean City, Maryland. Updip from these boreholes, the Calvert Formation, of latest Oligocene-middle Miocene age in Delaware, unconformably overlies middle Eocene glauconitic sands of the Piney Point Formation. The juxtaposition of the downdip mid-Oligocene rocks against the updip middle Eocene rocks can best be explained by a fault between the two regions.
The Delaware Academy of Science has been instrumental in informing Delaware citizens about science and utilization of local resources. Since 1970 the annual meeting of the Delaware Academy of Science has been used as a time for presentation of ongoing research in various areas of science in the Delaware region. The proceedings of these meetings have resulted in publication of transactions of the Delaware Academy of Science. The 1976 annual meeting focused on aspects of the geology of Delaware. Members of the Delaware Geological Survey and the Geology Department at the University of Delaware contributed papers in their specific disciplines. This volume presents an overview of studies of geological features and processes of evolution of the geology of Delaware. Although this collection of papers does not represent an all-inclusive study of the subject, the selections included in this volume highlight past, present, and future trends in the study of Delaware's geology. It is hoped that the combined bibliographies of all the papers will provide a comprehensive view of the literature for further investigation into the geology of Delaware.
OFR21 A Guide to Fossil Sharks, Skates, and Rays from the Chesapeake and Delaware Canal Area, Delaware
In recent years there has been a renewed interest by both amateur and professional paleontologists in the rich upper Cretaceous exposures along the Chesapeake and Delaware Canal, Delaware (Fig. 1). Large quantities of fossil material, mostly clams, oysters, and snails have been collected as a result of this activity. Recent dredging (1978, 1981) by the United States Army Corps of Engineers has helped expose a rich vertebrate fossil assemblage. It includes representatives from the classes Reptilia, Osteichthyes, and Chondrichthyes. An extensive literature search has revealed that a wealth of information exists which would aid in the identification of the vertebrate fossils of Delaware.
OFR4 Papers Presented by Staff Members of the Delaware Geological Survey at the Baltimore Meeting of the Northeastern Section of the Geological Society of America, March, 1974
This report is a compilation of four papers presented by DGS staff members at the Baltimore Meeting of the Northeastern Section of the Geological Society of America, March, 1974.