Geology and Geography of Georgia Lab

Pamela J. W. Gore
Georgia Perimeter College

Pamela J. W. Gore, 1997-2007, 2012

1. Georgia contains a number of physiographic provinces which have distinctive landforms, which are dictated by the rock types and geologic structures. The provinces can be recognized on satellite images and relief maps. Using the physiographic province map http://www.georgiaencyclopedia.org/nge/Multimedia.jsp?id=m-9031  or http://www.georgiaencyclopedia.org/nge/Multimedia.jsp?id=m-9031 and the relief map of Georgia http://fermi.jhuapl.edu/states/maps1/ga.gif, carefully examine the landforms and draw as carefully as possible the outlines of the following five physiographic provinces on the relief map. The lines between provinces should correspond with changes in the physiography (landforms). Neatly label the name of each province in the margin of the map.

  1. Coastal Plain
  2. Piedmont
  3. Blue Ridge
  4. Valley and Ridge
  5. Appalachian Plateau (Lookout Mountain area)

2. Using the Geological Highway Map of the Southeastern Region, you will determine the ROCK TYPE (rock names, such as granite or sandstone) and the AGES (geologic period name, or era) of the rocks which underlie each region. You will have to look at the individual colored areas on the map. Each of these colored areas is a rock unit, with a symbol that is an abbreviation of its age (and in some cases, rock type/name or formation name).

Southeastern Region Geological Highway Map (Pvp (Series), Vol. 352.) 

After you locate a rock unit (such as the red mPzg in the Piedmont region), look at the "Generalized Chart of Surface Time and Rock Units" on the map (center, bottom). Find the column labeled "Georgia", and carefully look for the color and symbol (such as mPzg). Also note that along the left side of the chart there is a geologic time scale, which will help you make sense of the symbols. In this case, mPzg means "middle Paleozoic granite". (See if you can find it in the column under igneous rocks.)

For the sedimentary rocks, the legend shows a generalized stratigraphic column with lithologic symbols. Each pattern indicates a particular rock type (these are shown in black and white in the Legend in the lower left part of the chart. (Dots indicate sandstone, bricks indicate limestone, etc.) If you plan to take Historical Geology, you will want to become familiar with these symbols.

a. Draw the lithologic symbols of the following rock types in the spaces provided:

Sandstone

Siltstone

Shale

Limestone

Dolomite

Conglomerate

 

 

 

 

 

 

 

 

 

 

 

 

 b. Determine ALL of the rock types (rock names) and ALL of the ages of the rock units in each province, and put them in the chart below.

Province

Rock Names

Ages

(Period/era names, not dates)

 

Coastal Plain

 

 

 

 

 

 

 Piedmont

 

 

 

 

 

 

 Blue Ridge

 

 

 

 

 

 

 Valley and Ridge

 

 

 

 

 

 

 

Appalachian Plateau

 

 

 

 

 

 

 3. Look at the geologic cross-section and green tectonic map with the lines of the cross-sections indicated, on the back of the map, and answer the following questions about geologic structures.

a. Which province is characterized by plutons and faults?

____________________

b. Note that the rocks of the Coastal Plain dip. (See chapter on crustal deformation in your textbook or lab manual if you need a review of this term). In which compass direction do they dip?

_____________________

c. Which province is characterized by folded sedimentary rocks and thrust faults?

______________________

d. Locate the buried Triassic Red Beds in the cross section. Which province are they buried beneath?

______________________

e. What type of fault (normal or reverse) bounds the edges of this buried basin?

______________________

4. a. Find the Chattahoochee River on the geologic map. It runs along a relatively straight line across the state. This line is a fault zone. What is its name? (It is labeled on the map.)

______________________

b. On your relief map of Georgia, carefully draw the trace of this fault, and label it with its name.

5. a. The Piedmont and Valley and Ridge provinces are separated by a fault in northwestern Georgia. What is its name? (It is labeled on the map.)

________________________

b. Describe (compare and contrast) the appearance of these two provinces on the relief map of Georgia. (describe the terrane: hilly? linear ridges? rugged? broad flat valley?)

The Valley and Ridge is:

 

 

The Piedmont is:

 

 

 

6. There are two major mountainous regions in Georgia, the Blue Ridge Mountains and the Valley and Ridge. Describe (compare and contrast) the appearance of these two provinces on the relief map of Georgia. (Describe the terrane: hilly? linear ridges? rugged? broad flat valley?)

The Blue Ridge is:

 

The Valley and Ridge is:

 

 

7. The coast of Georgia is marked by a series of barrier islands, often called Sea Islands.

a. Looking at the map, list the names of these islands in order from north to south.

1.

2.

3.

4.

5.

6.

7.

8.

9.

b. Using the map colors and symbols, what is the age (period name - not date) of the sediment that makes up these islands? Look for the color and symbol on the map, and refer to the "Generalized Chart of Surface Time and Rock Units". Find the symbol, and note the age (period name) from the geologic time scale along the left side of the chart.

___________________________

 

8. Inland, within 50 miles of the coast, is a series of sandy ridges that parallel the coastline. They are colored dark orange, and each ridge has its own map symbol. (Example: Qwi = Quaternary Wicomico. Find it on the map and in the chart at the bottom before proceeding further. They will be near the top of the Georgia Sedimentary Rock column because they are young.)

Each of these sandy ridges represents an old barrier island from a time when sea level was higher in this area. Using the chart on the map, list the names of each of these old shoreline sand ridges. One of them is Wicomico (pronounced wye-COM-uh-co). Now list the names of the others.

1.

2.

3.

4.

5.

6. Wicomico

 

9. Find Stone Mountain on the map. It is EAST of Atlanta, and on the map it is a small red body elongated in an east-west direction. Just to the left of it, is its symbol, Cs.

a. What is its age (period name - not date)?

_______________________

b. What is its rock type (rock name)?

_______________________

c. Approximately how large is this body (in square miles)? Look for the map scale. Multiply length times width (in miles).

_________________________mi2

Convert square miles to square kilometers. To convert square miles to square kilometers, multiply by 2.59. Or see the mathematical conversion factors in the front of your lab manual.

_________________________km2

d. Is Stone Mountain a stock or a batholith?

_________________________

Batholiths are intrusions covering an area of 100 km2 or more.
Stocks are intrusions covering an area less than 100 km2.

e. From an examination of the geologic map, would you agree with the statement that we sometimes hear, that the rock unit at Stone Mountain extends under much of Georgia, and into other neighboring states? (This is a common misconception among residents of the area.)

Is it true or false? ______________________

Why (justify your answer with data from this map and its cross-sections)?

 

 

 

 

 

 

 

f. Find the largest granite body in the state. It is the Elberton granite. (East of Athens.)

How many square miles does it cover?

________________________ mi2

How many square kilometers does it cover?

________________________ km2

 

g. Is the Elberton granite a stock or a batholith?

____________________________

 

10. See the copy of the geologic map of the Stone Mountain area, with formation descriptions for "Southern Piedmont Province and Brevard Fault Zone" From the Georgia Geologic Survey, Geology of the Greater Atlanta Region, Bulletin 96, McConnell and Abrams, 1984.
Click here to print out the map key in two parts. Map Key Part 1, Map Key Part 2

You will need colored pencils, crayons or markers to color certain units on the map as follows:

a. Color the amphibolite (amp) bodies purple or dark blue. There are some within the Stone Mountain Granite (Cs).

b. Color the Stone Mountain Granite (Cs) red.

c. Color the Promised Land Formation (pl) light blue.

d. Locate the diabase dikes (lines labeled "d"). Color them dark green.

e. In which compass direction(s) do the diabase dikes trend? (North-south? Northeast-southwest? Northwest-southeast?)

____________________________

 

f. What types of rock are found in the Clairmont Formation (cl), which surrounds the Stone Mountain Granite on its western end? (List two rock names.)

 

____________________________

 

____________________________

Refer to this chart of the metamorphic grade, metamorphic rocks, and index minerals before you answer the questions below.

Metamorphic Grade Metamorphic Rocks Metamorphic
Index Minerals
Low (about 200° C) Slate
Phyllite
Chlorite
Muscovite
Biotite
Intermediate Schist Garnet
Staurolite
Kyanite
High (about 800 ° C)
(verging on melting)
Gneiss
Migmatite
Sillimanite

g. In the Clarkston Formation (ca), which metamorphic mineral represents the highest grade of metamorphism?

____________________________

h. Based on the metamorphic index minerals present, which formation is more highly metamorphosed? The Clarkston Formation, the Promised Land Formation, or the Clairmont Formation?

____________________________

i. In terms of grade of metamorphism (based on the metamorphic index minerals), is the Snellville Formation (and its members) more like the Clarkston Formation, the Promised Land Formation, or the Clairmont Formation?

____________________________

j. From your course notes or textbook in the metamorphic rock chapter, what is the name of the very high grade metamorphic rock that has been subjected to such high temperatures that it has partially melted?

____________________________

k. Which formation on this map contains rocks which were metamorphosed to the point that they began to be partially melted? (Color it light green on the map.)

 

l. Name all of the formations or rock units that come into contact with the Stone Mountain Granite.

____________________________     ____________________________

____________________________     ____________________________

____________________________

m. Is the Stone Mountain Granite a concordant pluton or a discordant pluton?

____________________________

n. What rock types would you expect to find as xenoliths in the Stone Mountain granite, based on this map? (Hint: Look at the rock types it intrudes.)

____________________________     ____________________________

____________________________     ____________________________

____________________________

o. Is the Stone Mountain granite younger or older than the rocks it intrudes?

___________________

Why? (Explain your reasoning; justify your answer.)

 

 

 

 

 

11. Marble is mined in Georgia.

a. Marble is the metamorphosed equivalent of what sedimentary rock?

____________________________

b. Which geologic province in Georgia contains the marble deposits? (Check the legend under Metamorphic Rocks to find the marble, then look for that color and symbol on the map.)

____________________________

c. On the Southeastern region map, marble is the purple unit labeled "Lpzm", Lower Paleozoic marble. It belongs to a particular named formation. Check the chart and give its name.

_____________________ Marble

12. Locate the Tallulah Falls Dome on the Southeastern Region map. It is in the far northeastern corner of Georgia.

a. Study the diagrams of domes in your course notes, textbook, and/or lab manual. Determine whether the rocks exposed in the center of a dome are older or younger than the rocks around the edge of a dome.

____________________________

b. In the center of the Tallulah Falls Dome is a rock unit shown in dark yellow or light orange and labeled "q". It is metamorphic. Find it in the chart at the bottom of the map. From the list of names given beside this symbol, what is the formation name of this unit?

____________________________

13. Locate the Towaliga Fault on the Southeastern Region map. (It is between Atlanta and Columbus, GA). Notice the dark yellow units of quartzite near it (Hollis Quartzite of the Pine Mountain Group). The Hollis Quartzite underlies Pine Mountain near Callaway Gardens. (Quartzite is a ridge-former.)

a. Label the Towaliga Fault on your satellite image.

b. Label the Hollis Quartzite on your satellite image.

Water seeping down along the fault is heated at great depth, and then moves upward through the quartzite deposits. The naturally warm water in this area produces a particular geologic feature which was the reason that one of our former U.S. presidents moved to this area. The feature is also the name of a town in this area.

c. What is the geologic feature produced by the water?

____________________________

d. Who was the President? _________________________

e. Why did he want to be near this particular geologic feature?

 

There is a hint on the back of the map (#20).

14. Kaolin, a white clay made of the mineral kaolinite, is mined in Georgia. It is used in glossy coatings on paper, tire manufacturing, ceramics, etc. The kaolin deposits are of Cretaceous and Tertiary age. Find them on the map. They are shown in green with map symbol "Tku" (Tertiary and Cretaceous undifferentiated). 
(Note:  The term "Tertiary" is an older term that is no longer widely used; rocks of that age are now assigned to the Paleogene and Neogene periods.)

In which physiographic province is the kaolin located?

____________________________

15. The dome of the State Capitol in Atlanta is covered by 43 ounces (2.7 lb) of gold that was mined in Georgia, and donated in 1956. Fresh gold was reapplied in 1981.

Where in Georgia is gold mined (site of the first U.S. mint, before the Civil War)? (Name the city or town).

____________________________
 


Return to Georgia Geoscience Online

Lab written 1997 By Pamela J. W. Gore
Page created November 13, 1998
Updated October 22, 1999
Link added Nov. 17, 2000
Link added Nov. 19, 2001
Modified November 30, 2006
Links revised November 13, 2008
Modified April 17, 2012