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Site content related to keyword: "Miocene"

Bethany Formation

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The composition, thickness, and geophysical log signature of the Bethany Formation vary with location and depth. In general, the Bethany Formation is a sequence of clayey and silty beds with discontinuous lenses of sand (Andres, 1986; Ramsey, 2003). The most common lithologies are silty, clayey fine sand; sandy, silty clay; clayey, sandy silt; fine to medium sand; sandy, clayey silt, and medium to coarse sand with granule and pebble layers. Thin gravel layers occur most frequently in updip areas and are rarer in downdip areas. Sands are typically quartzose. Lignite, plant remains, and mica are common, grains of glauconite are rare. In the Lewes area, Ramsey (2003) describes the Bethany Formation as consisting of gray, olive gray, bluish-gray clay to clayey silt interbedded with fine to very coarse sand. Lignitic and gravelly beds are common.

DGS Geologic Map No. 15 (Georgetown Quadrangle) Dataset

DGS Geologic Map No. 15 (Georgetown Quadrangle) Dataset

This vector data set contains the rock unit polygons for the surficial geology in the Delaware Coastal Plain covered by DGS Geologic Map No. 15 (Geologic Map of the Georgetown Quadrangle, Delaware). The geologic history of the surficial geologic units of the Georgetown Quadrangle is primarily that of deposition of the Beaverdam Formation and its subsequent modification by erosion and deposition of younger stratigraphic units. The age of the Beaverdam Formation is uncertain due to the lack of age-definitive fossils within the unit but is thought to be between late Pliocene to early Pleistocene in age. Refer to Ramsey, 2010 (DGS Report of Investigations No. 76) for details regarding the stratigraphic units.

To facilitate the GIS community of Delaware and to release the geologic map of the Georgetown Quadrangle with all cartographic elements (including geologic symbology, text, etc.) in a form usable in a GIS, we have released this digital coverage of DGS Geological Map 15. The update of earlier work and mapping of new units is important not only to geologists, but also to hydrologists who wish to understand the distribution of water resources, to engineers who need bedrock information during construction of roads and buildings, to government officials and agencies who are planning for residential and commercial growth, and to citizens who are curious about the bedrock under their homes. Formal names are assigned to all rock units according to the guidelines of the 1983 North American Stratigraphic Code (NACSN, 1983).

GM15 Geologic Map of the Georgetown Quadrangle, Delaware

GM15 Geologic Map of the Georgetown Quadrangle, Delaware

The geologic history of the surficial geologic units of the Georgetown Quadrangle is primarily that of deposition of the Beaverdam Formation and its subsequent modification by erosion and deposition of younger stratigraphic units. The age of the Beaverdam Formation is uncertain due to the lack of age-definitive fossils within the unit. Stratigraphic relationships in Delaware indicate that it is no older than late Miocene and no younger than early Pleistocene. Regional correlations based on similarities of depositional style, stratigraphic position, and sediment textures suggest that it is likely late Pliocene in age; correlative with the Bacons Castle Formation of Virginia (Ramsey, 1992, 2010).

Marine Mammals: Phylum Chordata

Marine Mammals:  Phylum Chordata<br>Source:  seasky.org

The Pollack Farm Site, in the Cheswold sands of the lower Miocene Calvert Formation, produced a fragmentary marine mammal fauna. The Pollack location yielded at least six cetaceans (whales, porpoises), a sirenian(manatee), along with one of the earliest records of a true seal (Listed below).

Land Mammals: Phylum Chordata

Land Mammals:  Phylum Chordata<br>Source:  hedweb.com

Land mammal fossils were discovered in 1992 in the lower part of the Calvert formation at the Pollack Farm site. During the short time the pit was open, the collection grew to become the most diverse tertiary land mammal fauna known north of Florida on the eastern half of North America.

Birds: Phylum Chordata

Birds - Miocene Fossils <br>Source:  Wikimedia Commons

The lower Miocene Pollack Farm Fossil Site has yielded few avian fossils in comparison to the other classes of vertebrates and invertebrates. Only eleven fossil fragments, assignable to six taxa, were collected at the Pollack site. Of the eleven avian fossils collected, representations from three distinctive orders were recovered: Gaviiformes (divers and loons, seen below), Charadriiformes (gulls and shore birds), Pelecaniformes (cormorants and pelicans).

Reptiles: Phlyum Chordata

Reptiles: Phlyum Chordata<br>Source:  resalliance.org

The Pollack Farm Site has provided the first legitimate window of Miocene reptilian life in North America east of the great plains and north of Florida. In years prior to the excavation of the Pollack site, records of particular small lizards and snakes were non-existent in locations of the mid-Atlantic and northeast, thus providing a significant value to the Miocene fossils recovered.

RI75 Stratigraphy and Correlation of the Oligocene to Pleistocene Section at Bethany Beach, Delaware

RI75 Stratigraphy and Correlation of the Oligocene to Pleistocene Section at Bethany Beach, Delaware

The Bethany Beach borehole (Qj32-27) provides a nearly continuous record of the Oligocene to Pleistocene formations of eastern Sussex County, Delaware. This 1470-ft-deep, continuously cored hole penetrated Oligocene, Miocene, and Pleistocene stratigraphic units that contain important water-bearing intervals. The resulting detailed data on lithology, ages, and environments make this site an important reference section for the subsurface geology of the region.

RI47 Ages of the Bethany, Beaverdam, and Omar Formations of Southern Delaware

RI47 Ages of the Bethany, Beaverdam, and Omar Formations of Southern Delaware

The microflora of the Bethany formation and the lower part of the Beaverdam Formation is characterized by a Quercus-Carya assemblage, very few non-arboreal pollen, and Pterocarya and Sciadopitys as exotic constituents. This assemblage has much in common with that of the Brandywine Formation of Maryland and the Eastover Formation of Virginia which are of late Miocene or early Pliocene age. The environment of deposition of the Bethany was probably deltaic, and that of the lower Beaverdam fluviatile.

Miocene Fossils Overview

Miocene Fossils of Pollack Farm

Located in Kent County, Delaware, the Pollack Farm Site was a surprise to many to contain numerous fossils. The fossils discovered range from a simple Arthropod, small insect, to large vertebrates, such as sharks. In 1991, while Delaware Geological Survey staff collected earth minerals during a highway construction, they came across an upper shell bed full of molluscan fossils. As digging continued numerous fossils of various species and phylum were found.

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?

Tusk of Mammut americanum (American mastodon) discovered from the bottom of Delaware Bay after being caught in a scallop dredge. Pleistocene age.

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.

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.

B13 Geology, Hydrology, and Geophysics of Columbia Sediments in the Middletown-Odessa Area, Delaware

B13 Geology, Hydrology, and Geophysics of Columbia Sediments in the Middletown-Odessa Area, Delaware

Columbia sediments in the Middletown-Odessa area are composed of boulders, gravels, sands, silts and clays. These sediments are exposed in four gravel pits where their structures and textures were studied. Subsurface geology was interpreted on the basis of the well-log data from 40 holes drilled in the area of study. Columbia sediments were laid upon a surface made up of the greensands of the Rancocas Formation (Paleocene – Eocene age). The contact between the Rancocas and Columbia Formations is an erosional unconformity.

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.