Page 353 - Laboratory Manual in Physical Geology

A CTIVIT Y 12.2 Karst Processes and Topography

Name: ______________________________________ Course/Section: ______________________ Date: ___________

A. Analyze FIGURES 12.4 and 12.5 .

1. In the area photographed in FIGURE 12.4 , there is no soil developed on the limestone bedrock surface, yet abundant plants

are growing along linear features in the bedrock. What does this indicate about how water travels through bedrock under
this part of Oklahoma?
2. If you had to drill a water well in the area pictured in FIGURE 12.4 , where would you drill (relative to the pattern of plant

growth) to find a good supply of water? Why?
3. REFLECT & DISCUSS How is FIGURE 12.5 related to FIGURE 12.4 ?

B. It is common for buildings to sink into newly formed sinkholes as they develop in karst regions. Consider the three new-
home construction sites (labeled A, B, and C ) in FIGURE 12.2 , relative to sinkhole hazards.

1. Which new-home construction site ( A, B, or C ) is the most hazardous? Why?

2. Which new-home construction site ( A, B, or C ) is the least hazardous? Why?
3. REFLECT & DISCUSS Imagine that you are planning to buy a new-home construction site in the region portrayed in
FIGURE 12.2 . What could you do to find out if there is a sinkhole hazard in the location where you are thinking of building

your home?

C. Study the orthoimage of the Park City (Kentucky) topographic map in FIGURE 12.3 . Almost all of this area is underlain by

limestone. The limestone is overlain by sandstone in the small northern part of this image (Bald Knob, Opossum Hollow)
that is covered by dense dark green trees.

1. How can you tell the area on this orthoimage where limestone crops out at Earth’s surface?

2. Recall that on a topographic map, a depression is shown by a contour line, with hachures (tic marks), that forms a closed
loop. Describe the pattern of depressions on the topo map of Park City. Why do some of the depressions contain ponds,
while others do not?
3. REFLECT & DISCUSS Notice that there are many naturally formed circular ponds in the northwest half of the image.
(The triangular ponds are surface water impounded behind dams constructed by people.) How could you use the
elevations of the surfaces of the ponds to determine how groundwater flows through this region?

D. Refer to the map on the back of this page, a topographic map of the orthoimaged area in FIGURE 12.3 .

1. Compare the map and orthoimage, then draw a contact (line) on the map that separates limestone with karst topography
from forested, more resistant sandstone. Color the sandstone bedrock with a colored pencil.
2. Gardner Creek is a disappearing stream . Place arrows along all parts of the creek to show its direction of flow, then circle

the location where it disappears underground. Circle the disappearing end of two other disappearing streams.
3. Notice that there are nine different springs that flow from the east-west trending hill on which Apple Grove is located.

Label the elevation of each spring (where it starts a stream), then use the elevation points to draw a flow line with a large
arrow to show the direction that water travels down the hydraulic gradient within the hill.

4. Find and label a solution valley anywhere on the map.
5. REFLECT & DISCUSS Notice that a pond has been constructed on the sandstone bedrock on top of Bald Knob and
filled with water from a well. If the well is located on the dark blue edge of the pond, then how deep below that surface
location was the well drilled just to reach the water table? Show your work.

323