Geology of Virginia
Why? Pulls together what they already know: Rocks
Plate Tectonics Wilson Cycles Geologic Structures
Stratigraphic Principles/Sequence of Events Geologic Time Map and Cross Section Interpretation
ES.8 The student will investigate and understand geologic processes including plate tectonics. Key concepts include a) how geologic processes are evidenced in the physiographic provinces
of Virginia including the Coastal Plain, Piedmont, Blue Ridge, Valley and Ridge, and Appalachian Plateau; b) processes (faulting, folding, volcanism, metamorphism, weathering,
erosion, deposition, and sedimentation) and their resulting features; and c) tectonic processes (subduction, rifting and sea floor spreading, and continental collision).
Defining Characteristics of PC: formation of Earths crust and main
bombardment first life appears first multicellular animals at end of interval
Defining characteristics from Smithsonian site (link on portaportal): http://www.nmnh.si.edu/paleo/geotime/main/index.html
Grenville Orogeny
Grenville Orogeny As A Cordilleran (Andean-type) Orogeny
Rocks now exposed in the Blue Ridge Formed deep below the mountain roots.
Virginia ~ 1 Billion Years Ago Grenville Mountains Would Have Looked Like These Modern Andes Mountains
http://www.astro.uni-bonn.de/~maltmann/photgal_cz
Late Precambrian Supercontinent This map illustrates the break-up of the supercontinent, Rodinia,
which formed 1100 million years ago. The Late Precambrian was an "Ice House" World, much like the present-day.
Cambrian Rifting Defining Characteristics of the Cambrian:
Cambrian Explosion skeletonized animals early animal diversification
Antietem Sandstone base of Blue Ridge, Luray, Virginia
Antietem: Quartzites Protoatlantic DCM
Conocheague: Limestone & Dolomite
Conocheague: Intertidal Taconic Orogeny
Edinburg Limestone Page Valley east of Luray: deep water black limestones
Martinsburg Page Valley east of Luray: turbidity sandstones and shales Defining Characteristics of Ordovician:
diversification of marine invertebrate Paleozoic Fauna end-Ordovician extinction During the Ordovician ancient oceans separated the barren continents
of Laurentia, Baltica, Siberia and Gondwana. The end of the Ordovician was one of the coldest times in Earth history. Ice covered much of the southern region of Gondwana.
Interorogenic Calm
Acadian Orogeny Defining Characteristics of the Devonian:
Age of Fishes diverse land invertebrates and first land vertebrates diversification of vascular plants
http://brattahlid.tripod.com/sw3-73webb.htm
http://www.pbs.org/wgbh/nova/link/hist_05.html Interorogenic Calm
100's of meters above present sealevel
6 5 4 3 2 1 0
Qt. rising
KASKASKIA SEA
SAUK SEA 6
5 4 3 2 1
100's of meters above present sealevel
0 Cretaceous
Juriassic Protero. Cambrian
Ordovicin TIPPECANOE SEA
Silurian Devonian
Miss ABSAROKA
SEA Pennsylv.
Perm Triassic
present sealevel Tertiary
falling
Mississippian Carboniferous Coal Swamps
http://www.coe.ilstu.edu/iga/IMCanal/IMCanal/coal.jpg
Alleghanian Orogeny Continent-Continent Collision Orogeny
Himalaya Mountains
http://www.cliffshade.com/colorado/tectonics. Atlantic Rifting
Pre-rifting
Early Rifting Rifting
Continued Rifting Opening of Atlantic
Continued Rifting Opening of the Atlantic Continued Rifting Opening of the Atlantic
Triassic Rift Basins
Triassic Dinosaur Footprints from Eastern North America The Atlantic Rifting Zone, especially the basins of the Newark Supergroup, are famous for their
reptile footprints. Tens of thousands of Triassic and Jurassic tracks have been found since they were first recognized in 1836 by Edward Hitchcock. The tracks of Triassic age are especially important because they document the rise to dominance of the dinosaurs. They are also very,
very well preserved. Grallator parallelum track from Furnace Hill, PA.
(track found by Mike Szajna and Brian Hartline) Theropod tracks called Grallator and
Anchisauripus appear in Newark Supergroup rocks in strata of early Late Triassic age and become larger and more abundant into younger
strata. The structure of this kind of track suggests that it was probably made by a small (?young) theropod dinosaur similar to
Coelophysis. Reconstruction of Atreipus based on the hypothesis that it was made by an ornithischian dinosaur. From Olsen and
Baird (1986). http://rainbow.ldeo.columbia.edu/courses/v1001/10.html
Atlantic DCM
Rejuvenation Well-preserved layer of material ejected from Chesapeake Bay meteor-strike discovered
http://www.spaceref.com/news/august2004.html
