GEOLOGY of VIRGINIA

Prepared by:

Miss Sasha Dofflemeyer

Earth Science Bell-to-Bell Lesson

Class of Mr. Stephen Deer

Held on December 11, 2009

4th Block

Windows into the World:

SOL Standards MetES.8 The student will investigate and understand geologic

processes including plate tectonics. Key concepts include:

• how geologic processes are evidenced in the physiographic provinces of Virginia including the Coastal Plain, Piedmont, Blue Ridge, Valley and Ridge, and Appalachian Plateau;

• processes (faulting, folding, volcanism, metamorphism, weathering, erosion, deposition, and sedimentation) and their resulting features; and * tectonic processes (subduction, rifting and sea floor spreading, and continental collision).

Definition of Terms

Learning ObjectivesAfter this lesson, students should be able to:

•Determine how Virginia’s physiographic provinces provide evidence for geologic processes.•Identify the major events in Virginia’s geological history.•Know the basic rocks from the physiographic provinces and why and how they got there. •Know how to use clay modeling as a study technique.

5 Physiographic Provinces of Virginia

• Including the Triassic basic, but discluding the eastern shore.

5 Major Provinces of Virginia

Clay Modeling of Provinces

-Coastal Plain- Piedmont- Triassic Basin- Blue Ridge- Ridge and Valley- Appalachian Plateau

Quick Review: Rocks and Minerals

• Mineral: homogeneous, naturally occurring, inorganic solids.

• Rock: made up of one or more minerals.

• Igneous Rocks: Formed from the cooling of molten rock.

• Sedimentary Rocks: Formed in layers as the result of moderate pressure on accumulated sediments.

• Metamorphic Rocks: Formed from older "parent" rock (either igneous or sedimentary) under intense heat and/or pressure at considerable depths beneath the earth's surface.

Coastal Plain• Extends from the Fall

Zone to the Atlantic Ocean

• Unconsolidated or partially consolidated sediments , i.e. “loose”

• At the Fall Zone, larger streams begin to erode igneous and metamorphic rocks, transporting them to the Coastal Plain as much smaller fragments.

Piedmont• Largest physiographic

province, bounded on the east by the Fall Zone and on the west by the mountains of the Blue Ridge.

• Characteristically, this province has gently rolling topography and deeply weathered igneous and metamorphic bedrock.

Triassic Basin• Basin formed when

Africa separated from North America to create the Atlantic Ocean.

• Consists mainly of lower Mesozoic sedimentary deposits, also displays lower Jurassic rocks in smaller quantity.

• Culpeper Basin is the largest, but others exist in Richmond, Farmville, and Danville amongst other places.

Blue Ridge• Includes the Blue Ridge

Mountains (Skyline Drive and the Blue Ridge Parkway.

• The physiography and geology do not correspond.

• Blends in topographically with the Piedmont, yet has a different type of igneous rock.

Valley and Ridge• This province is bounded in

the East by the Blue Ridge Mountains and in the West by the Allegheny Plateau.

• Western boundary is called the Allegheny Front.

• This marks an abrupt change from flat lying sedimentary rocks of the Plateau to folded/faulted rocks in the valley and ridge.

Appalachian “Allegneny” Plateau

• Southwestern Virginia, most of this is contained in West Virginia.

• Rocks are flat and sedimentary.

• The rocks display a dendritic drainage pattern. The rugged terrain is explainable by this type of erosion.

• Dendritic – splitting in a random pattern.

How do scientists reconstruct the

geological history of an area? What tool do they

use?

FOSSILS

Our state fossil, Chesapecten jeffersonius found in Chincoteague, VA

This fossil is an Early Pliocene indicator, this species flourished about 4.5 – 4.3 million years ago.

Geologic Time Chart

• 1.37 billion years ago, proto-North America collided with other continents to form a large supercontinent that we now call Rodinia. (Mountain Building Event)

• Following the Greenville Mountain building, the North American plate began to crack away from the other continental plates in the Late Precambrian and Early Cambrian. A series of rifts occurred, creating the Iapetus or Proto-Atlantic Ocean. (Ocean Forming Event)

• About 380 million years ago, proto-Africa collided with North America to create the central and southern Appalachians, Pangea forms (Mountain Building Event).

• During the Jurassic, the final break up between North America, Gondwana and Baltica happened. The rift occurred along the mid-Atlantic Ridge, fragmenting Pangea and moving the continents closer to their current position. This is the birth of the Atlantic Ocean (Ocean forming Event)

Major Events

Geologic Map of Virginia

The Rifting Model

The Colliding Model

Sources• http://csmres.jmu.edu/geollab/vageol

/vahist/index.html• http://web.wm.edu/geology/virginia/?

svr=www• http://priweb.org/ed/TFGuide/SE/se_g

eohist/se_geohist_pdfs/geo_history_se.pdf

• Many thanks to the James Madison

and College of William and Mary Geology Departments!