Week Two (Starting September 5, 2005): Geology of Virginia

1) read the objectives for the week

2) read the online lecture materials: TIME MANAGEMENT REMINDER: This is one of the most challenging weeks in trhe course. A lot of the links below are to maps, because geology is easier to visualize than to read. Be sure to visit each page assigned below (if there's a hotlink, then it's assigned...), but you don't need to follow every one of the additional links on each of those assigned pages to other websites until you find the end of the Internet. Quiz materials will come just from the Web pages specifically assigned each week.

Of course, you're encouraged to explore and discover things through serendipity, as well as do the assigned work. Carve out the time and stretch your brain. In a few months, you'll forget if Va Tech beats UVA in football (again...) or Ward Burton's status in the latest NASCAR rankings - but years from now, you might still remember why the state boundary between Maryland and Virginia is not the middle of the Potomac River, or why there are barrier islands on the coastline of Virginia.

• Let's start at a very basic level. Examine Ray Sterner's shaded relief map of Virginia, noting differences in the shape of the land from east to west in particular. In your brain, divide Virginia into two parts and draw a line separating the "flat east" region from the "bumpy west" region of the state.

(If your only maps are road maps, you might find a place -
but you'll miss the geology and much more of the geographic context...)
• Read Physiographic Regions Introduction
• Read the Physiographic Regions of Virginia
• Contrast the descriptions of the Physiographic Regions on two excellent sites, Susan Woodward's excellent depiction of Physiographic Provinces of Virginia (at Radford University) and William and Mary's wonderful Geology of Virginia site. Start by reading the Physiographic Provinces of Virginia, then follow the links on the Radford site to the separate geologic cross-sections for all 5 physiographic provinces: Coastal Plain, Piedmont, Blue Ridge, Valley and Ridge, and Appalachian Plateau:
  • Coastal Plain and geologic cross-section
  • Piedmont and geologic cross-section
  • Blue Ridge and geologic cross-section
  • Valley and Ridge and geologic cross-section
  • Appalachian Plateaus and geologic cross-section
• Move on to the William and Mary site. This may be a ho-hum refresher for you if you remember earth science or a starting point to understand the terminology of geology, but be sure to look at:
  • Geology of Virginia
  • Virginia Geologic Map
  • Virginia Geologic Cross-Section
  • Geologic Rock Cycle
  • A Brief Tectonic History of Virginia
• (Forgotten 8th grade Earth science? Use the Geologic Time Chart of Virginia pages to refresh your memory of the geologic terms and the sequence of the Precambriam/Paleozic/Mesozoic/Cenozoic eras and the geologic periods known as "Ordivician" and "Triassic.")
• After you got a grip on the basics, follow the links below to read about all 5 physiographic provinces on the William & Mary site:
• Coastal Plain and Generalized Stratigraphy of Virginia's Coastal Plain
• Piedmont and Simplified Piedmont for Students & Teachers
• Blue Ridge and Simplified Blue Ridge for Students & Teachers
• Valley and Ridge and Simplified Valley & Ridge for Students & Teachers
• Appalachian Plateau and Simplified Appalachian Plateau for Students & Teachers

Can you find Massanutten Mountain? (Hint: revisit the radar image you saw last week...)
In which physiographic province is it located?
Source: Visible Earth, by NASA


• Go back to Ray Sterner's shaded relief map of Virginia. In your brain, decide where you would draw a line separating the 5 physiographic provinces: Coastal Plain, Piedmont, Blue Ridge, Valley and Ridge, and Appalachian Plateau. Can you identify the location of the Chesapeake Bay, after looking at other maps of Virginia? Can you find the southern border of Virginia, using the location of the Chesapeake Bay? Can you identify the Continental Shelf east of Virginia's Eastern Shore, using the image to the right? Feel free to revisit the Radford and William and Mary websites until you could draw the approximate boundaries of the Coastal Plain, Piedmont, Blue Ridge, Valley and Ridge, or Appalachian Plateau on the state highway map, if that was part of a quiz question such as "In what physiographic province is Winchester located?"
• Read Rocks and Ridges - Where Did Virginia Get Its Mountains and Valleys?
• Read how Virginia was assembled at Using Cereal Bowls and Car Crashes to Understand Virginia Geology. Follow the links to:
• The Grenville Event and Virginia Geology
• The Orogeny Zones and Virginia Geology
• The Rest of the Story About Virginia Geology
• Examine a portion of the United States Geological Survey (USGS) A Tapestry of Time and Terrain: The Union of Two Maps - Geology and Topography site:
• Coastal Plain
• Fall Line
• Appalachian Valley and Ridge
• Watch Virginia grow, from the bottom up, by looking at the different layers of rocks deposited over the last 1.2 billion or so years and get a horizontal "CAT scan" of Virginia bedrock:
• Precambrian Rocks (see the line of the Blue Ridge in Virginia?)
• Cambrian and Ordovician Rocks and Silurian and Devonian Rocks (see the limestones, shales, and sandstones that form today's hills and valleys in the Valley and Ridge province?)
• Mississippian and Pennsylvanian Rocks (see the coal regions on the Appalachian Plateau?)
• Triassic and Jurassic Rocks (as described in the Virginia Journey: The Stones Beneath Your Feet video, when did the rocks under the Manassas battlefield form?)
• Cretaceous Rocks (only a small section of Virginia was underwater then. Cretaceous sediments were not deposited west of the Fall Line, because the Piedmont, Valley and Ridge, and Appalachian Plateau were exposed above the ocean surface and eroding away...)
• Lower Tertiary Rocks (gee, think the Eastern Shore is gonna turn out to consist of the youngest exposed bedrock in the state?)
• Quaternary Rocks (the most recent deposits)
• Look at Hydrogeomorphic Regions in the Chesapeake Bay Watershed, and find the boundaries of the Coastal Plain, Piedmont, Blue Ridge, and Valley and Ridge. (Why can't you find hydrogeomorphic boundaries that match up with the edges of the Appalachian Plateau physiographic province? HINT: does the map include all of Virginia, or just the portion north of the James River?)
• Compare the boundaries of the physiographic provinces in the physiographic map of Virginia with the separate regions identified by the state's Natural Heritage Program. Why would they be different?

Source: USGS: A Tapestry of Time and Terrain
• Whew! Now that you have rocks in your head, you can understand how physical geography is so fundamental to the cultural geography of Virginia. Read a series of short "overview" pages on:
• Fall Line
• Waterfalls of Virginia
• Caves and Springs in Virginia
• Role of the Blue Ridge
• Role of Coal and Coal in Virginia
• Glaciers and Ice Ages in Virginia (note how the continental shelf was once dry land... and occupied by the earliest settlers. Go 5 miles off the current coastline, and you might find arrowheads under the more-recent sediments...)
• Popsicle Planet
• read the entire The Chesapeake Bay Bolide: Modern Consequences of an Ancient Cataclysm (it's actually pretty short...)
• Introduction
• Ancient Cataclysm
• Location of Chesapeake Bay
• Continued Differential Ground Subsidence
• Disruption of Coastal Aquifers
• Ground Instability Due to Faulting
• Summary

3) Watch the Virginia Journey video: The Stones Beneath Your Feet

4) Complete the Web Exercise: Go to the US Geological Survey's National Atlas Follow the link to "Click Here to Make Maps" (the graphic in the upper right) and you should see this:

Select the "Zoom to State" button

Select Virginia, of course, and then select "Geology":

Scroll down to "Shaded Relief," one of the checkboxes offered under the heading of Geology. Note that you will use the scroll bar on the far right of the screen

Find the "Redraw" button again and click it to - surprise - redraw the map:

After all this effort, you should see:

Now, identify on the redrawn image the boundaries of the physiographic provinces - Coastal Plain, Piedmont, Valley and Ridge, Appalachian Plateau, and make special note of the location of the Fall Line. Try zooming in to get a map showing less of the state, in more detail:

Each inch on the redrawn map will then correspond to a smaller number of inches on the ground, and it will take a larger monitor or piece of paper to show all of the state. Will that new, zoomed-in image on the screen now be a smaller-scale map, or a larger-scale map? (If you're looking for a reason to post a listserver message and earn those points for this week, indicate why you think the redawn, zoomed-in map is a larger-scale or a smaller-scale map.)

Before you zoom in, about 6 inches corresponded to the entire length of the southern border of Virginia - roughly along a parallell of latitude at 36 degrees, 30 minutes north of the equator. Zoom in enough, and 6 inches on the map might correspond to just the distance between False Cape State Park and Interstate 95.

5) Complete the Map Exercise: Using the Delorme Atlas and Gazetteer, find the highest elevation on I-95 between Washington, DC and the North Carolina border, and compare it to the highest elevation of I-64 between Norfolk and the West Virginia border. What is the approximate elevation of the high point of I-95, compared to the approximate elevation of the high point of I-64 in Virginia?

6) Complete the Site Visit: Find a road cut, construction project - or make your own hole in the ground in your back yard - and note the characteristics of the bedrock or deepest layer of soil you can see exposed. Is it predominantly pale sand, orange clay, purple sandstone, black basalt, greenstone, gray limestone?

7) Complete Quiz #1 on WebCT, covering material from previous weeks (i.e. questions on Quiz #1 come from material covered through Week One. However, I expect problems in the logistics of making the videos available via the library or for sale via STAR, so Quiz #1 will not include questions from the "Edges of Virginia" video last week.

Schedule your time according to the Deadlines:
September 8 - Quiz #1 goes on WebCT
September 11 - Quiz #1 due at midnight
September 13 - last day to drop class without any tuition liability

Other dates that might interest you:
September 11: The Fairfax County Park Authority will host the Virginia Indian Festival at Riverbend Park on September 10, with representatives of different Virginia tribes. Use the Geographic Names Information System and you’ll get a solid clue about the historic location of the Nottoway tribe, based on places named after them (Fort Nottoway, Little Nottoway River, Nottoway Falls Reservoir...).