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Site content related to keyword: "Upper Cretaceous"

Dinosaurs in Delaware?

Only fragmentary remains of dinosaurs have been found in Delaware. All of these have come from the Chesapeake and Delaware Canal, mainly from the spoil piles created by the dredging of the Canal. Various nature groups in Delaware lead trips to the Canal for collecting. Most of the fossils found are those of marine invertebrates (primarily bivalves and gastropods with some remains of sponges, ammonites, and belemnites).

Magothy Formation

Km

Dark-gray to gray silty clay to clayey silt that contains abundant fragments of lignite; grades downward into a very fine to fine sand with scattered and discontinuous thin beds of clayey silt with lignite fragments. Thickness ranges from 20 to 50 ft. Updip in the vicinity of the Chesapeake and Delaware Canal, the Magothy fills channels incised into the Potomac Formation and is discontinuous in its extent. Interpreted to have been deposited in coastal to nearshore environments.

Merchantville Formation

Kmv

Light- to dark-gray, very micaceous, glauconitic, very silty fine- to very fine-grained sand to fine sandy silt. Ranges from 20 to 120 ft in thickness. Marine in origin.

Englishtown Formation

Ket

Light-gray to white, micaceous, slightly silty to silty, fine-grained, slightly glauconitic quartz sand. In outcrop, it is extensively burrowed with Ophiomorpha burrows. Ranges from 20 to 50 ft in thickness. On the cross-section, the Englishtown is shown only where the sands are well developed. Interpreted to be nearshore marine to tidal flat in origin.

Marshalltown Formation

Kmt

Greenish-gray, slightly silty, fine-grained glauconitic quartz sand. Glauconite comprises 30 to 40 percent of the sand fraction. Ranges from 10 to 50 ft in thickness. Extensively burrowed. Interpreted to be marine in origin.

Navesink Formation

Generally a calcareous silt that is slightly to moderately sandy and slightly to moderately clayey. Sand is fine to very fine grained composed of about 50 percent glauconite, 40 percent peloids, and 10 percent quartz. Sediment is laminated, marked by varying amounts of clay and sand. Peloids are yellow to yellowish-brown flat to ovoid pellets that are calcareous and may contain flakes of chitin and grains of glauconite or quartz. Scattered shell fragments are present but form a minor constituent of the sediment. Uniformly dark-greenish-gray, slightly lighter in color than the overlying Hornerstown Formation. 10 to 20 ft thick.

Mt. Laurel Formation

Kml

Slightly calcareous, glauconitic, quartz sand that is medium to fine grained. Contains about 3 to 5 percent glauconite. Sand is subrounded to subangular and slightly silty with a few moderately silty zones. Scattered belemnites are present as well as a few scattered shell fragments or thin shell beds. Uniform dark olive gray or yellowish-brown where weathered. In outcrop, reported to be extensively burrowed (Owens, et al., 1970). Where it is the surficial deposit south of the Chesapeake and Delaware Canal, the Mt. Laurel can be confused with the Columbia Formation, especially where the color is similar. Can be differentiated by ubiquitous presence of glauconite and generally better sorted sands of the Mt. Laurel. Marine in origin. Ranges from 30 to 100 ft in thickness.

Hornerstown Formation

KTht

Glauconite sand that is silty and slightly to moderately clayey and contains scattered shell beds. Glauconite approximately 90 percent to 95 percent of the sand fraction and quartz 5 percent to 10 percent. Near the top of unit, silt-filled burrows are present. Lower, the unit is commonly laminated with silty sand and moderately clayey sand. Silt and clay matrix is calcareous. Uniformly a dark-greenish-gray. Interpreted to be marine in origin. The Cretaceous-Tertiary boundary is considered to lie within the formation. Rarely occurs in outcrop and where shown on the map is covered by colluvium along the stream valley bluffs. Ranges between 10 and 50 feet in thickness.

RI71 Internal Stratigraphic Correlation of the Subsurface Potomac Formation, New Castle County, Delaware, and Adjacent Areas in Maryland and New Jersey

RI71 Internal Stratigraphic Correlation of the Subsurface Potomac Formation, New Castle County, Delaware, and Adjacent Areas in Maryland and New Jersey

This report presents a new time-stratigraphic framework for the subsurface Potomac Formation of New Castle County, Delaware, part of adjacent Cecil County, Maryland, and nearby tie-in boreholes in New Jersey. The framework is based on a geophysical well-log correlation datum that approximates the contact between Upper and Lower Cretaceous sediments. This datum is constrained by age determinations based on published and unpublished results of studies of fossil pollen and spores in samples of sediment cores from boreholes in the study area. Geophysical log correlation lines established above and below the datum approximate additional chronostratigraphic surfaces. The time-stratigraphic units thus defined are not correlated parallel to the basement unconformity, as in previous practice, but instead onlap it in an updip direction. In future studies, the sedimentary facies of the Potomac Formation within each time-stratigraphic layer may be mapped and analyzed as genetically related contemporaneous units. This new stratigraphic framework will allow better delineation of the degree of lateral connection between potential aquifer sands, thus enhancing understanding of aquifer architecture.

Fossil Sites In Delaware

Fossil sites near the C&D Canal

Delaware offers a few sites for fossil collectors, and the Chesapeake and Delaware Canal and the Pollack Farm are the best. Other locations throughout the state also offer good hunting grounds for fossil collectors. Just south of Dagsboro, where Route 113 crosses Pepper Creek, the collector can find young (less than 2 million year old) marine fossils from the Pleistocene Epoch. At the state sand and gravel pit just south of Middletown on Route 896, plant impressions from the Pleistocene may be found.

What is a fossil?

What is a fossil?

If you think you may have found a Delaware dinosaur or any unusual fossil, the scientists at the Delaware Geological Survey at the University of Delaware, Newark campus would like to see it. It could provide important information on the geologic history of the First State.

RI37 Stratigraphic Nomenclature of Nonmarine Cretaceous Rocks of Inner Margin of Coastal Plain in Delaware and Adjacent States

RI37 Stratigraphic Nomenclature of Nonmarine Cretaceous Rocks of Inner Margin of Coastal Plain in Delaware and Adjacent States

Rocks of Cretaceous age deposited in continental and marginal environments, and now found along the inner edge of the northern Atlantic Coastal Plain, have historically been classified as the Potomac Group and the Potomac, Patuxent, Arundel, Patapsco, Raritan, and Magothy formations. Subdivisions of the Raritan and Magothy formations have also been recognized. Lithologic characteristics and spatial relationships of the units indicate that only the Potomac Formation and the Magothy Formation can be differentiated in northern Delaware. The complex nonmarine deposits originated on an aggrading coastal plain. Their projections into the deeper subsurface on- and offshore will be important in future studies. No changes in terminology are recommended, but careful use of stratigraphic nomenclature is urged in order to avoid confusion, especially in hydrologic applications.

B20 Stratigraphy of the Post-Potomac Cretaceous-Tertiary Rocks of Central Delaware

B20 Stratigraphy of the Post-Potomac Cretaceous-Tertiary Rocks of Central Delaware

This Bulletin presents the subsurface stratigraphy of the post-Potomac Cretaceous and Tertiary rocks of the Atlantic Coastal Plain of central Delaware, between the Chesapeake and Delaware (C & D) Canal and Dover. Geophysical log correlations supported by biostratigraphic and lithologic data from boreholes in Delaware and nearby New Jersey provide the basis for the report. The stratigraphic framework presented here is important for identifying subsurface stratigraphic units penetrated by the numerous boreholes in this part of Delaware, particularly those rock units that serve as aquifers, because such knowledge allows for better prediction at ground-water movement and availability. Also, accurate stratigraphy is a prerequisite for interpreting the geologic history of the rocks and for the construction of maps that depict the structure and thickness of each unit.

B18 Clay and Clay-Size Mineral Composition of the Cretaceous-Tertiary Section, Test Well Je32-04, Central Delaware

B18 Clay and Clay-Size Mineral Composition of the Cretaceous-Tertiary Section, Test Well Je32-04, Central Delaware

This study complements Delaware Geological Survey Bulletin No. 17 and deals exclusively with clays and clay-size minerals. The cored section at the location of Je32-04 has been subdivided into 25 clay zones on the basis of major changes in trends and degree of crystallinity of clay minerals. The composition of clay minerals varies from zone to zone. These clay minerals have been identified: kaolinite, berthierine, chlorite, illite, smectite, chlorite/smectite, illite/smectite, glauconite/smectite, and glauconite pellets. Other minerals present in the section include: zeolites (clinoptilolite-heulandite), gypsum, and elemental sulfur.

B17 Geological Studies of Cretaceous and Tertiary Section, Test Well Je32-04, Central Delaware

B17 Geological Studies of Cretaceous and Tertiary Section, Test Well Je32-04, Central Delaware

A cored well 1,422 feet (433 meters) deep drilled two miles southeast of Dover is the basis for this integrated study of the lithology and paleontology of the Cretaceous-Tertiary section in central Delaware. The section is subdivided into lithostratigraphic, biostratigraphic, chronostratigraphic, and heavy mineral units. Data and results are presented on a common base in three plates.

Coastal Plain Rock Units (Stratigraphic Chart)

The geology of Delaware includes parts of two geologic provinces: the Appalachian Piedmont Province and the Atlantic Coastal Plain Province. The Piedmont occurs in the hilly northernmost part of the state and is composed of crystalline metamorphic and igneous rocks. This chart summarizes the age and distribution of the geologic units that are recognized in the state by the Delaware Geological Survey.

Geologic History of the Delaware Coastal Plain

In Delaware, the oldest unit of the Atlantic Coastal Plain is the Potomac Formation. Sediment eroded from the Appalachian Mountains was deposited in rivers and swamps in a tropical climate along the margins of the forming ocean during the latter part of Early Cretaceous time, about 120 million years ago.

RI21 Guide to Common Cretaceous Fossils of Delaware

RI21 Guide to Common Cretaceous Fossils of Delaware

This guide contains illustrations of fossils from Delaware Geological Survey Bulletin No. 3 ("Marine Upper Cretaceous Formations of the Chesapeake and Delaware Canal") and Report of Investigations No. 7 ("An Invertebrate Fauna from the Upper Cretaceous of Delaware"). The identifications have been revised to be as accurate as possible so that this guide will be useful to those fossil collectors interested in classifying their "finds."