• Introduction
  • The Rocks
  • New England
    • New England Formations
  • New Jersey to Virgina
    • New Jersey to Virginia Formations
  • The Carolinas
    • Formations in the Carolinas
  • Georgia
    • Formations in Georgia
  • Florida
    • Florida Formations
  • Localities
  • Maps and Figures
    • Geologic Maps
    • Formations
  • References

Introduction

The modern Atlantic Ocean apparently started to open around 200 million years ago at the end of the Triassic Period and in the early part of the Jurassic period. Rift Valley deposits from that time are discussed in another writeup. Oddly perhaps, No sedimentary deposits are known in Eastern North America from the 50 or so million years after the ocean started to open. However, beginning in the Early Cretaceous around 130 million years ago, we start to see sediments that were deposited along the Atlantic Margin of North America. The oldest beds are continental lowland deposits -- presumably coastal swamps. These are superseded further East by a patchwork of Upper Cretaceous and later marine and lowland deposits. The general trend is for the oldest deposits to be found furthest West, but there are places where Cretaceous beds lie along the coast and others where Tertiary deposits are found 100km inland from the coast. In most places, the coastal deposits are buried under unfossiliferous recent debris. Since the coastal plane is generally pretty flat, fossiliferous exposures tend to be confined to stream beds, sea cliffs, quarries, canals, and occasionally road cuts. The underlying bedrock consists of metamorphic Iapetus seafloor rocks and possibly some Triassic Basin rocks

The Atlantic Margin beds extend from SouthEastern Massachusetts to Florida. I have -- quite arbitrarily -- excluded most Pleistocene, Holocene and very recent fossiliferous deposits often found in anomalous places such as Canada's Ottawa River Valley and will discuss them in a separate Terrane writeup.

I have also -- again arbitrarily -- excluded deposits along the Gulf Coast similar to those of the Atlantic margin. Those deposits have a more or less uniform stratigraphic terminology that differs from the contemporaneous Atlantic margin deposits. And they serve as a bridge into the Cretaceous Inland Sea deposits of the plains and Rocky Mountain states and provinces. They will be discussed in another writeup.

The Rocks

Ideally, it might be best to put everything into a single table with states across the top from Florida on the left to Massachusetts on the right and geologic age on the vertical axis. But pragmatically that would require a lot of scrolling to get to the right side. So, I'll break this into tractable subsets.

In general, the deposits are unaltered and often poorly consolidated sediments. The terrestrial rocks are siltstones, shales, clays and conglomerates. Fossils consist of a few vertebrate bones and teeth and occasional plant fossils. The marine rocks are shales, sandstones and limestones. Invertebrate fossils are very common. In some places, marine vertebrates and fish teeth and bones are quite common.

New England

Atlantic margin rocks in New England and New York exist only along offshore islands and a small area in SouthEastern Massachusetts. Where present, they are usually buried under glacial debris and are very poorly exposed. Known exposures of Cretaceous beds are on Long Island, Staten Island, Block Island and the Elizabeth Islands near the South side of Cape Cod. Eocene deposits are exposed in SouthEastern Massachusetts. Cretaceous, Miocene and Pleistocene exposures occur on Marthas Vinyard. Pleistocene fossils are found on Nantucket.

New England Formations

New Jersey to Virgina

Atlantic margin beds are found in New Jersey East of a line from the head of Raritan Bay to the Delaware River at Trenton and thence Southward through Wilmington, Delaware, and Maryland through the North central part of the District of Columbia then South to Smithfield, NC.

New Jersey to Virginia Formations

Limestone Fossiliferous (Igneous/Metamorphic)

The Carolinas

The Atlantic Margin formations are found East of the line from Richmond, Virginia to Smithfield, North Carolina. From there the outcrop is offset West to a point SouthWest of Raleigh and then Southwest through Columbia, SC to Augusta, Georgia.

Formations in the Carolinas

Limestone Fossiliferous (Igneous/Metamorphic)

Georgia

The Atlantic Margin beds are found South of a line from Augusta on the Georgia-South Carolina border West to and beyond Montgomery, Alabama. These beds largely use the same nomenclature as the Gulf Margin beds further West.

Formations in Georgia

Limestone Fossiliferous (Igneous/Metamorphic)

Florida

The entire Florida Peninsula including the Panhandle is covered by Atlantic Margin beds.

Florida Formations

Limestone Fossiliferous (Igneous/Metamorphic)

Localities

• Big Brook Park, Marlboro, Monmouth County, NJ -- Cretaceous vertebrate remains in stream gravels. Near Vandenburg Rd and Boundary Road bridges over the stream. Collecting of small amounts from the gravesl (not the banks) is permitted http://www.fossilguy.com/sites/bbrook/

• Poricy Brook Preserve, Monmouth County, NJ -- Cretaceous fossils -- mollusks, shark teeth. Collecting of small amounts from stream bed (but not banks) is permitted. Access from Nature Center at 345 Oak Hill Road Middletown, NJ? https://en.wikipedia.org/wiki/Poricy_Park

• Chesapeake and Delaware Canal, New Castle County, DE -- Cretaceous mollusks, a few shark teeth. Collecting permitted from old spoil piles near Reedy Point Bridge, St Georges, Summit Bridge and elsewhere.

• Calvert Cliffs, Calvert County, MD -- Miocene mollusks and shark teeth between Chesapeake Beach and Drum Point. Public access is limited and may require a fee, but is available at Chesapeake Beach, Plum Point, Calvert Cliffs State Park, and Flag Pond. Collecting is permitted along beach, but not in cliffs.

• Yorktown, York, VA -- Area exposures, streams, road cuts, etc between Williamsburg and Yorktown. Abundant, well preserved, Miocene mollusks. A few vertebrates. Legality of collecting is questionable, but permission can probably be obtained.

• Aurora -- The Gulf PCS Phosphate Mine at Aurora, Beaufort County, NC is a major source of Miocene and Pliocene mollusks and vertebrate teeth. Collecting at the mine is restricted to a few weekend days a year with slots signed up in advance and tightly allocated, but dump material from the mine is said to be available at the Aurora Fossil Museum as well as in local DWP road material dumps and in areas in the region that have been filled with mine material.

• Lake Waccamaw -- A wide variety of Cretaceous and Miocene mollusks and vertebrate fossils are reported from Lake Waccamaw, Columbus County, NC. These are mostly found washed up on the shore. But they are said to be common buried in the lake sand, in a low bluff along the North Shore, and North of North Carolina 214. Public access is along the South Shore at the State Park

• Peace River -- Along the Peace River, DeSoto County, Florida between Gardner and Acadia, Florida at times of low water. Fossils are generally found on the creek bottom rather than the banks and are collected by scooping/diving. Pliocene and Pleistocene land and marine vertebrates.

• Tampa -- In Miocene outcrops in Tampa Bay and in area excavations. Miocene Fossils -- silicified corals, mollusks, vertebrates. Sharks Teeth were once abundant 30 km to the South along the beach at Venice, but beach reclamation projects in the late 20th Century are said to have covered the offshore beds from which the fossils were eroding.

Maps and Figures

Geologic Maps

Massachusetts State map (simplified) http://geology.about.com/library/bl/maps/blmassachusettsmap.htm State map http://www.geo.umass.edu/stategeologist/frame_maps.htm

Rhode Island

Connecticut State maps https://web.archive.org/web/20200306154657/http://www.wesleyan.edu/ctgeology/images/CtGeoMap_big.jpg

New York Generalized Bedrock Geology of NY

Overview of NY Geology

New Jersey Simplified map of NJ

Index to online geology maps of New Jersey

Pennsylvania Simplified map of PA

Digital Geologic map of Pennsylvania

Delaware

Map of Cretaceous outcrops on C&D Canal (Note, the original link I used was faulty or has vanished. Hopefully this is the same document) -

Maryland Geologic Map

Virginia

North Carolina Generalized map

Access to detailed maps

South Carolina

Georgia High Resolution map

Florida Generalized map

Formations

See Rocks

References

• THE PLEISTOCENE DEPOSITS OF SANKOTY HEAD, NANTUCKET, AND THEIR FOSSILS. JOSEPH AUGUSTINE CUSHMAN. NANTUCKET, MASS. FEBRUARY 1906. https://archive.org/details/pleistocenedepos00cushrich

• https://web.archive.org/web/20100801203109/http://www.mvtimes.com/news/2007/02/08/lucy_vincent_fossils.php

• http://paleoportal.org/index.php?globalnav=time_space&sectionnav=state&name=Massachusetts

• http://people.hofstra.edu/J_B_Bennington/research/cretaceous/kplantfossils.html

• https://web.archive.org/web/20130325133450/http://www.library.csi.cuny.edu/dept/as/geo/sigeo.htm

• ADDITIONS TO THE PALEOBOTANY OF THE CRETACEOUS FORMATION ON STATEN ISLAND. NO. II. Arthur Holiick. (Read May 16, 1898.) Google Books

• Upper Cretaceous and Tertiary Formations of the New Jersey Coastal Plain

• A Description of the Fossil Fish Remains OF THE Cretaceous, Eocene and Miocene Formations of New Jersey

• Delaware Geologic Survey Cretaceous Fossils of Delaware. A description of Cretaceous outcrops along the C&D Canal

• Geologic Maps of Maryland: Coastal Plain Rocks and Sediments

• The clay deposits of the Virginia coastal plain By Heinrich Ries, William Bullock Clark, Benjamin LeRoy Miller

• The coastal plain of North Carolina By William Bullock Clark, Benjamin LeRoy Miller

• Actinopterygian Fish Remains from the Paleocene of South Carolina

• 2001 Cenozoic Strat Column (Converted)

• DETAILED GEOLOGIC MAPPING OF AQUIFER RECHARGE AREAS IN THE UPPER COASTAL PLAIN OF SOUTHWEST GEORGIA Mark D. Cocker?

• Florida State Geologic Map

Copyright 2006-2012 Donald Kenney (Donald.Kenney@GMail.com). Unless otherwise stated, permission is hereby granted to use any materials on these pages under the Creative Commons License V2.5.

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