Exploring Georgia's Natural History
  • Natural History & Geology
    • Podcast; The Tivola Whale
    • Coastal Plain Correlation Chart
    • GA Paleo Research by Paul F. Huddlestun PhD >
      • Late Eocene & Older... Coastal Plain Stratigraphy
      • Washington County Core Logs By Paul Huddlestun
      • Coastal Plain Core Logs by Paul F. Huddlestun
    • Presentation; Oaky Woods Stratigraphy
    • Physiographic Map of Georgia
    • Fossils of Oaky Woods
    • Collections & Stewardship of Georgia’s Fossils
    • I, Periarchus (A Fossil's Tale)
    • Georgia's Amateurs >
      • Amateur; Jared Dyche, On The Way To A Degree
      • Cam Muskelly, Duluth, GA
      • Kyle Keller, Valdosta, GA >
        • Kyle Keller Returns, Still Rocking!
      • Hank Josey, Dublin
      • Bill Christy; Kamin Performance Minerals Fossils
    • Public Fossil Locations >
      • South Houston County Fossils
      • Updated; Islands of the Savannah River
    • Georgia Fossils in the Smithsonian
  • Education Material
    • My Field Kit; What You Need In The Field
    • Meet Crassostrea gigantissima, Georgia's Historic Giant Oyster
    • Georgiacetus Presentation; A Whale for Georgia
    • The Natural History & Fossils Record of Houston County, GA
    • Evolution in Georgia's Fossil Record
    • Georgia's State Fossil; Shark Teeth
    • Georgia's Paleontology For Georgia's Classrooms
    • SW GA RESA 2018 Talk
    • Library & School Presentations
    • An Introduction To Fossils; Presentation
    • Georgia's Fossils Presentation; 500 million years
    • Georgia College Natural History Museum
  • Meteorites
    • Did I Find A Meteorite?
    • Georgia's Lost Meteorite
    • Georgia's Witnessed Meteorite Falls
    • The Sardis Iron, Georgia's Largest Meteorite
  • 1: Georgia's Oldest Fossils; Archaeocyathids, At 513 Million Years Old
  • 2: Trilobites; 500 Million Years Ago
    • 2A; Murray County Stromatolites
    • 2B; A Trilobite Nest in Georgia
  • 3: Geologic Time
  • 4: Our Oldest Vertebrate?
  • 5: Georgia Before the Dinosaurs
    • 5A; Georgia’s Pennsylvanian Plant Fossils
    • 5B: Carpentertypus durhami, Georgia’s Giant Insect, 315 Million Years Ago
  • 6: 200 Million Years Ago
    • 6A: Birth of the Atlantic Ocean
  • 7: Cretaceous Georgia, Dinosaurs & more
    • 7A: Georgias Pterosaur
    • 7C: Coelecanths
    • 7B: So Many Sharks
    • 7D: Xiphactinus vetus
    • 7E: Side-necked turtles
    • 7F: Marine Reptiles
    • 7G: Dinosaurs in Georgia
    • 7I; The Blufftown Formation
    • 7L: Bill Montante's Mega "Gator" Tooth Discovery
    • 7K: The Pio Nono Formation
    • 7J: The Eutaw Formation
    • 7H: Deinosuchus schwimmeri in Recognition of Dr. David Schwimmer
  • 8: Suwannee Current, Gulf Trough, & Bridgeboro Limestone
  • 9: The Clayton Formation Report; By Hank Josey
    • 9A: The Georgia Turtle
  • 10: The Eocene; Georgia's Oldest Mammals
    • 10A: The Origins of Whales
  • 11: A Whale For Georgia
  • 12: Basilosaurids; The First Modern Whales
    • 12A: Basilosaurus cetoides
    • 12B: Basilotritus
    • 12C: Cynthiacetus (Revised)
    • 12D: Chrysocetus
    • 12E: The Redmond Mandible of Albany Ga
    • 12F; Houston County, GA Basilosaurus to the Smithsonian
  • 13: Ziggy and The Museum of Arts & Sciences, Macon, GA
  • 14: Late Eocene
    • 14A: Eocene Fossils & Stratigraphy
    • 14B; Fossils, Impacts, & Tektites Dating the Clinchfield Formation
    • 14C: The Tivola Limestone
    • 14D: Twiggs Clay Vertebrates
    • 14F; Sandersville Limestone, By Hank Josey
    • 14E: Ocmulgee Formation Vertebrates
    • 14I: Dating Late Eocene Sediments
    • 14J: Georgia's Tektites; Georgiaites
    • 14K; Shell Bluff; Georgia's Most Historic Paleontology Site
    • 14L; Taylors Bluff, Paleo Paddling the Ocmulgee River
    • 14M; Eocene Terrestrial Mammals From Gordon, GA
    • 14N: Fossil Ridge, A Stratigraphic Study in Oaky Woods Wildlife Management Area
    • 14O; Georgia's First Entelodont
    • 14P: Historic Rich Hill
    • 14Q; Bibb County's Christy Hill, Clinchfield Formation Hilltop
  • 15: Early Oligocene
    • 15A: The Marianna Limestone
    • 15B; The Glendon Limestone
    • 15C: Undiffereniated Oligocene Residuum
    • 15D; Brissus bridgeboroensis; A New Echinoid Species From Georgia’s Bridgeboro Limestone
    • 15E: The Curious Steinkern Sea Biscuits of Red Dog Farm Road
    • 15F: Early Oligocene Gordian Knot
  • 16: Bonaire GA Entelodont
  • 17: The Whale Eating Shark
  • 18: Miocene Epoch; 23.3 to 5.3 Million Years Ago
    • 18A; Miocene Terrestrial Vertebrates
    • 18B; Paul Fell, Rockhouse Cave
    • 18C: The Marks Head Formation
    • 18D: Miocene Terrestrial Vertebrates of the Marks Head Formation
    • 18E: The Statenville Formation
    • 18F: South Georgia’s Dugong Metaxytherium calvertense
  • 19: Pliocene Epoch; 5.3 to 2.5 Million years Ago
    • 19A; Two Small Primitive Horses from Taylor County
  • 20: The Ice Ages; Pleistocene & Holocene Epochs
    • 20A; Clark Quarry's Mammoths & Bison
    • 20B: Pleistocene Vertebrate List
    • 20C: Georgia’s Eolian Dunes
    • 20D: Georgia’s Carolina Bays
    • 20E: Late Pleistocene Significant Events
    • 20F: Southeastern Thermal Enclave
    • 20G; Diamond Back Terrapins
    • 20H; A Kaolin Mine Beaver Dam
    • 20I; Pleistocene Vertebrate Fossils On Georgia’s Piedmont
    • 20J; Watkins Quarry Pleistocene Vertebrates, Glynn County, GA
  • *NEW* 20K: Pleistocene Vertebrates from Coastal Georgia
  • 21: Humans in Georgia
  • 22: Geology of the Coastal Plain, 1911
    • 22A: 1911 Cretaceous Fossil Locations
    • 22B: 1911 Eocene Fossil Locations
  • 23: Coastal GA Locations (1957)
  • 24: Needed; The Georgia Geologic Survey
  • Building This Site
    • Origins Of This Site
    • Contributing Artists
    • Black & White Sketches

​6A: Birth of the Atlantic Ocean
By Thomas Thurman
​

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Our Hypsognathus knew only a tiny part of boundless Pangaea.

Boundless Pangaea; without ever seeing an ocean you could have walked from Australia, through Antarctica, through Africa, South America, Central America, North America, Canada, Greenland, Western Europe, Russia, China and beyond.

If we could visit Georgia during time of Hysognathus 200 million years ago we’d quickly notice that the Atlantic Ocean was missing. It simply didn’t yet exist; there was only Pangaea surrounded by a global ocean.

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Before the Atlantic Ocean could open Pangaea had to be split.

So how do you split a continent? 

We saw how 300 million years ago plate tectonics had formed Pangaea when the continents collided, buckling the terrain of Georgia’s Ridge and Valley Region.

The continents are restless. Today there is a volcanic seam along the length of the modern Atlantic Ocean floor which forms the Mid-Atlantic Ridge, the longest mountain chain in the world. It is completely submerged except for its northern-most limit in Iceland. 

Several tectonic plates are involved but essentially the Mid-Atlantic Ridge is where magma from Earth’s mantle rises through the Earth’s crust to the sea floor. Deep beneath the Atlantic’s waves it erupts as lava, providing new crustal material as it slowly pushes the continental plates apart. 

Today, the sea floor is spreading at about 2.5 centimeters (.98 inches) per year.



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The Mid-Atlantic Ridge created the Atlantic and began the slow process of splitting Pangaea. The splitting began with a rift, a seam, where rising forces were pushing the plates apart. 

The Dunbarton Basin and many other rift valleys along North America’s east coast represent early failures to split Pangaea. These are rifts that didn’t stick. 

About 200 million years ago one series of rifts did stick and began slowly splitting Pangaea, separating North America from Africa. Roughly 130 million years ago the Atlantic became a reality.

Dr. Burt Carter at Georgia Southwestern reminded me of this when he reviewed this website.

11/Dec/2014
Thomas
There’s another Africa connection.  The various rift basins in the eastern USA were failed attempts to open the Atlantic Ocean.  The basin that ultimately succeeded (where GA is concerned) was one whose walls were (very roughly, given subsequent erosion) where the continental slopes of N. America and Africa met.  That rift basin is still active as the Mid- Atlantic Ridge.  All the Atlantic oceanic crust between the original walls has been created since the Jurassic at that rift basin.  This is still one of the coolest realizations I have ever come to.
Burt
 
Think of that, the world’s longest mountain chain and hundreds of miles of sea floor which didn’t exist when our Hypsognathus lived. 
 
Dr. Pamela J. Gore, Professor of Geology at Georgia Perimeter College and author of Roadside Geology of Georgia (with William Witherspoon), is also very familiar with rift basins.   

17/Dec/2014
Thomas
Consider that Africa was attached to North America, with a volcanic island chain squeezed in between. A series of roughly parallel tension cracks began to form, as rifting began, and the cracks (at depth, not necessarily at the surface) filled with hot basaltic magma from below. These became the Triassic-Jurassic diabase dikes that we see exposed in some of the rock quarries and elsewhere in the Piedmont. One of these cracks became dominant with tremendous outpourings of basaltic lava, and became the Mid-Atlantic Ridge, forming the Atlantic Ocean basin.
Pamela
 
Pangaea was split, the Atlantic Ocean was born and the Earth moved closer to the world we all know and love.