Biology 2106 Environmental Lab

Lab 7: Visit to Texas Memorial Museum and Barton Springs

Time Required: Part A: 2-3 hours, Part B: 3-4 hours. PLEASE STOP BY MY RVS OFFICE TO PICK UP COPIES OF THE

ZILKER PARK MAPS BEFORE YOU GO! Maps will be on the door.

Part A: Texas Memorial Museum

 

The Texas Memorial Museum is located on the UT Campus 2400 Trinity Street D-1500 (for a map please refer to orientation handout, or go online to www.texasmemorialmuseum.org).Their phone number is (512) 471-1604. This is a show case of collections and work from faculty at the University of Texas, as well as collections of artifacts donated and loaned to the Museum. The museum has a variety of exhibits, accompanied by well-written explanations. And while not all exhibits are appropriate topics for this class, they are all well worth your time. So while this lab is limited to those exhibits that pertain to Environmental Biology, I strongly urge you to take the morning or afternoon off and allow 3-4 hours to visit all the exhibits.

The main purpose of Part A is to expose you to a cross-section of information including the geological processes that formed Texas, the biotic regions of Texas, the status of freshwater fish in Texas, and information about Waller Creek.

It is almost impossible to get free parking on campus. I strongly suggest that you park in visitor parking lot on Trinity St. just next to the museum. Depending on how long you stay, the parking will cost you $3-4. Once you have parked in the visitor-parking garage, the museum will be on the south side opposite of Bass concert hall. On the walkway between the parking garage and the museum is a small brick enclosed structure-it is on your left as you leave the garage and head to the museum. It looks like a mini building with one side covered in glass. Behind the glass you will see a collection of footprints.

  1. Describe what you see inside, drawing a picture if possible. You may wish to answer your questions on a separate sheet of paper.

 

 

Once inside the museum you will enter a large vestibule with an exhibit on gems and beetles and animals horns. Take a peek around- its nice. You are now on the second floor of the museum. You may wish to obtain a map of the museum so you can find the different exhibits on floors 1, 3 and 4.Please note, I have called the museum and the recorded message indicates that all these exhibits will remain up for spring. If you have any difficulties please let me know ASAP.

The focus of the first floor exhibit is to demonstrate how the land- form we call Texas was formed over billions of years. Various geological processes, such as volcanic activity, uplift, erosion and sedimentation have created the formations- such as the Davis and Guadeloupe Mountains in west Texas, and the Balcones Escarpment just west of Austin. You may know it as the Texas Hill Country. East of Austin we have the Coastal Plains (also known as the Blackland Prairie) which extends all the way to the Gulf of Mexico. It is not a coincidence that farm lands are typically found to the east of the Balcones Escarpment- where the soils are less rocky and thicker. In contrast, the Balcones Escarpment consists of coarse porous limestone. When it rains, the water quickly filters down through the limestone. Thus soils are much thinner and rockier in the Hill country- poor for farming, but better for ranching and building expensive houses with grand views. The geological formations also explain why landfills are built on the east side of Austin where black land clay soils are better at retaining the chemicals and liquids associated with a landfill. Thus many environmental decisions- where to build a landfill or nuclear power plant are influenced by the land itself.

  1. For each geologic period (there should be several) describe the major events that occurred within that time period and the organisms associated with each geological period. Describe the changes that occur in the Texas landscape over time.
  2. Biotic Regions of Texas (called Wildlife of Texas on the museum map)

This exhibit is located on the third floor of the museum. A biome is defined as an area of land that is predominated by a specific set of plants and animals. It is the largest defined "biological area’- compared to an ecosystem, for example, which is much smaller. The predominate forces that shape biotic regions a) the geological forces, b) the amount of precipitation, and c) the annual temperatures in that region. Since Texas covers such a large area, there are several distinct biotic regions within the state. The museum has dioramas depicting the flora and fauna of each biotic region. After you have examined the exhibit you should

  1. Name each region (giving both the formal and informal names) and describe what unique processes create each region. Then list several of predominate plants and animals you are likely to find within each region.

Fishes of Texas

This exhibit is found on the third floor of the museum and describes a) the diversity of freshwater species in Texas, b) the story of how several species have gone extinct and c) the processes that lead to the demise of different species.

  1. First watch the interactive video at the beginning of the display.
  2. Look at the Fish Tree that is located on the wall. While many of the species still exist, several have gone extinct. Examine the diagram and list how many species of freshwater fish have gone extinct.
  3. Next there is a wall display highlighting the plight of 4 different species of fish. Each species is endangered- but all for different reasons. List the 4 species and why each one is in danger.
  4. Next there is a display of fish. While all of the fish "look" like perch- not all of them are. How many of the species are actually perch? What are the other species?

Fossil Plants (also located on the third floor-see museum map)

The fossil plants are found in this last room where you have a showcase of plant and birds.

  1. Describe the 4 steps that occur when plants fossilize.
  2. What do fossilized plants have to do with environmental biology? (hint- why do we depend upon them. What will happen when the fossilized plants are all gone?
  3. In the back of this room there is a wall plaque called predator prejudice. What is the point of the information on the plaque?
  4. What can you infer about populations of other animals- especially humans from this plaque?

Biodiversity Exhibit (located on the 4th floor)

This section has lots of interesting stuff to look at- like the 3D turtle. Read about the Waller Creek Exhibit:

  1. What does this creek have to do with the city of Austin? What Does UT have to do Waller Creek?
  2. How has human urbanization affected the creek and the organisms that live along the creek

PART B: Geological and wildlife tour through Barton Springs and Zilker Park

Introduction

Zilker Park is considered by many people to be a environmental jewel in downtown Austin. It is unusual to have such a large expanse of recreational and undeveloped land only 2 miles from a state capitol. The once pristine Barton Creek and Barton Springs have been zealously guarded by the SOS coalition (Save our Springs). The coalition is a diverse group of citizens who have attempted to restrict building and development within the Barton Creek drainage area to prevent water quality damage. This group has come into direct conflict with developers who are attempting to put more and more housing developments in the drainage area. Barton Springs has had to shut down several times in the past few years due to high fecal coliform counts. Human and livestock waste has seeped into the Barton Springs drainage system due to houses and ranches that are too close and numerous to the springs. The result is a direct warning to Austinites: that the "jewel" of Austin can become a cesspool if citizens do not protect the environment. For more on the SOS coalition, please visit their web site www.SOSalliance.org to see what you can do to influence your local environment.

Some of you may have already visited the springs on a hot summer day. Others may have played frisbee or soccer in the park. The point of this informal walking tour is to allow you to see a city park from a different perspective- that of an environmental student who recognizes the delicate balance between nature and recreation. Please note you will need to provide documentation that you have visited the site- any receipt from the springs, dinosaur tracks or nature center will suffice.

The best time to take this 5km walking tour would be on a Saturday when the Dinosaur Trackways are open (normal hours are Sat. 9am-11am). You can also combine the tour with a swim at the springs. Bring a friend along and you can turn your homework into a day in the park!

To help with the tour I handed out a series of pictures and diagrams at orientation that will help explain the different stops. I cannot upload these pictures to the web, so if you missed orientation, you can make arrangements with me to pick up the additional materials before the tour.

Geological background of the Zilker Park area

Now that you have visited the Texas Memorial Museum in Part A of this lab, you have a basic feel for the millions of years it took to form the geology of Texas. Recall that most of the rocks that crop out in the immediate Austin area were deposited by a sea that began encroaching on this area throughout the Cretaceous period. This seaway eventually joined with the Cretaceous Inner seaway that extended from New Mexico up to Canada. The ocean receded as the Rocky Mountains were thrust upwards during the early Cenozoic. Further uplift of the Rockies, combined with an overall lowering of the sea level caused the ocean to withdraw to its present day coastline. The total thickness of the Cretaceous deposits are about 2500 ft and are filled with fossil remains of marine creatures including oysters, snails and foraminifers. Thus as you are walking along on this tour, the majority of exposed rock outcrops will consist of this Cretaceous limestones, dolomites, marls and clays. The limestone rock may be your best place to look for fossils remains.

The most prominent geological feature in the Austin area is the Balcones Fault Zone (see handouts, figure 5) which forms the major topographic feature- the Balcones Escarpment. This fault, which is considered inactive today is the area that separates the Hill Country to the west, from the gulf Coast Plain (also known as the Blackland Prairie. Recall from the earlier labs that this geological division helps determine where structure such as landfills are located. The general fault zone is about 5 miles wide, while the Balconies Fault is 750 ft. wide. Numerous springs arise from the fault zones. This explains why we have Balcones Springs in the middle of Austin.

The limestone rock you will see exposed along the 5km route is typical of the Edward’s Limestone of central Texas. It is interesting to note that the Colorado River, which meanders through Austin is most likely following the historical weaknesses in the general fault zone.

Stop 1: Cretaceous Tidal Flat Deposits.

Looking at Figure 2, you can see that the self-guided tour begins at the southeast corner of the parking lot where the ground slopes down just to your left as you enter the parking lot area. Drainage from the lot and picnic area adjoining the lot have eroded the soil, forming a small series of v-shapes bedding planes and exposures (see the handouts which give a diagrammatic sketch of the section at stop 1). In general, what you are seeing in the flat more "flaggy " section of the rock is the time when the sea way which covered this area was receding. In contrast, the upper sections depict a time when the water levels covering this area were rising. If you look closely in the middle of the flaggy section you will see layers of mudstone which are predominated by mudcracks where the edges of the cracks are diffuse and rounded. These softened edges were caused by ancient algae growing down into the cracks. In contrast, the mud layer just above this one is characterizes by sharp and angular mudcracks. This is due to the fact that the ancient algae were unable to grow at this "edge" of the sea (intertidal zone) because the mudflats here were exposed to the sun. Thus it has been suggested that you are now standing on the edge of what was an ancient lagoon- an isolated section of the seaway.

If you look above the mudstone, there is a 6-9 inch layer of limestone the upper surface being uneven and exposed. This upper surface is approximately from the same geologic time period as the exposed dinosaur tracks you will see later in the tour. On top of the dinosaur track zone is a zone filled with abundant vertical burrows. There are most likely to be the burrows of small invertebrate animals who built burrows in the mud, only to have the burrows filled in with grainstone over time. Finally, in the uppermost bed of 9-12 inches there is an abundance of fossils, primarily horn-shaped bivalve mollusks. You can recognize them by the striated appearance which almost looks like bone. You can also see some spiral shaped bivalves which are brownish in color. The diversity of animal life in this layer suggests that at this point in time this habitat was covered by a deeper open shelf layer of waters.

Stop 2: Stone-Faced Pillars

From stop 1, continue downslope alone the entrance road for 100 until you reach the stone pillars on either side of the road. The base of these pillars are made of native Texas stone. These include schist, sandstone and two kinds of limestone, as well as cobbles of chert (used to make arrowheads) quartz crystals and pink and gray granite This pink granite is the same stone that was used to build the State Capitol in downtown Austin.

Stop 3: Barton Springs Pool

Head southwest towards the bathhouse to view the Barton Springs Fault. Barton Springs pool is just south and downslope from the bathhouse. A fence surrounds the swimming pool area, but looking inside (if you chose not to go in and swim!) you can easily view the fault itself. Recall that the fault outcrop is the source of the Barton Springs which flows from a fissure in the rocks. You can see the fault near the stair rail into the water where the right side of the rock is slightly higher that the left side. The flow rate from the fault system varies from several million to 107 million gallons per day, depending upon time of year, and seasonal rainfall. This is right at the edge of the Edward’s limestone on its west side. This is a type of limestone that extends southwest Austin out towards Wimberley, TX (my own house in Driftwood sits on it). And towards San Antonio.

The rain waters which feed the spring (called the recharge area) come through fissures and seep down through the soil and the rock. Barton Creek is one of 6 creeks that feed this recharge area and thus the Springs itself. During dry months the creek does not flow all the way to the springs, since the water is captured by the ground cracks and fissures before it travels very far. During very heavy rains when the creek overflows and sends the excess water into the springs, Barton Springs is closed due to the threat of flash flooding, turbidity (which clouds the water) and the excess debris and non point source pollutants from urban runoff and fertilizer from yards- all which wash down into the springs.

Because the aquifer is a system of large fractures and small caves in the ground, pollutants that wash into the aquifer do not dissipate, but end up in the Barton Springs. Because the ecosystems of the Creek and Springs are so fragile, Austin citizens voted in 1992 to protect the water quality of the Barton Springs Zone. This measure, called the Save Our Springs ordinance, is one of the most stringent water protection laws in the United States. The ordinance has given birth to the SOS alliance that attempts to maintain a vigilant watch on developers and industry who attempt to circumvent the ordinance.

  1. As part of this lab, you will need to go to the SOS alliance web site (see above) and write a brief description of the current legal issues are endangering the springs, and the Edwards Aquifer in general

Stop 4: Zilker Ponds

From the west end of the bath house, go north across the parking lot to the top of the grassy slope. As you climb the slope you will see the remains of an old amphitheater to your left. If you go to the stairway and look to the left end of the fieldstone wall, the flagstone walkway and flagstone lined depression in front of you are the old Zilker Ponds. They extend for another 100 years to the east and were build in the 1930’s. The ponds (where the depressions are now) were built from the adjacent surrounding outcrops of rocks so well that is hard to tell where natural ends and man made structures begin. If you look carefully in limestone rock walkways you will see the same burrows, mudcracks and various fossils you saw in stop 1 of the tour. Zilker Gardens, built in the 1960’s, replaces these ponds, and they have eroded over time.

Stop 6: The Moonlight Tower

Looking at your map, skip step 5 (which is too geologically involved for our purposes) and head to the moonlight tower, just north of the Rock Garden parking lot (its hard to miss!)

The tower is 165 ft tall and is a replica of one of the 31 towers that were installed around Austin in 1895 to provide lighting for the citizens of Austin. Today there are still 17 towers in neighborhoods around Austin, (you can see another tower just west of 6th street on S. Lamar), although their original lighting system (carbon-arc) have been replaced with mercury vapor lights. These types of towers were fairly common in the 19th century. The ones in Austin are believed to be the only working ones left in the world. They are listed in the National Register of Historic places. The one you see here is a replica of the original which stood on this site. The original tower was torn down in 1967 since it was so badly damaged. Every December the tower is transformed into the Zilker Park Christmas tree which displays a huge spiral strand of light at night. Come down at Christmas time and you can stand under the tower looking up and spin around under the lights- a favorite Austin tradition and well worth the experience!

Stop 7: Zilker Park Dinosaur Parkways

From Stop 6 go northwest through an open filed towards the crest of Barton Creek Road (see map). Cross the road and into the Zilker Botanical Gardens. Bear right through the parking lot to reach the Garden Building. Follow the map (through the rose garden) to the dinosaur tracks. There is a two dollar requested admission charge. This goes towards the upkeep of the area and can serve as your confirmation that you have visited the site. Please attach the receipt for either the springs or the trackway to your lab so that I can give you full credit for your visit.

You can pick up an information sheet as you enter, and there should be a guide to answer your questions. In 1991, huge rains in Central Texas produced extensive flooding. If you lived here in 1991, you may remember flooding along Shoal Creek. This flooding washed out an abandon limestone quarry in the Zilker Gardens exposing ancient dinosaur tracks, plant fossils and the partial remains of a turtle. Paleontology students from Austin Community College excavated this site as a class project. The turtle was discovered by the curator of the Texas Memorial Museum. The rest of the tracts are still being worked on. The tracts you see here correspond to the large mudstone layer you saw in stop 1: in other words they were laid down at approximately the time. The tracks themselves vary in size from 15-28 centimeters and are believed to be the footprints of a three-toed bipedal dinosaur.

Stop 8: The Austin Nature Center

From Stop 7, head west along Stratford Drive- see the map and watch for traffic! Pass under the freeway and follow the signs for the Nature Center.

The Nature Center admission should be free, although they do ask for a $2.00 admission. Again, this receipt can serve as your documentation that you have visited the site.

There is a Visitor Pavilion, Wildlife exhibit, Birds of Prey exhibit and Nature trails to explore.

Stop and spend as much time as you like looking at the native animals and examining the displays on natural ecosystems of Austin.

  1. As part of this lab write up, you will turn in several detailed paragraphs describing the ecosystems display, and the wildlife exhibit. Compare these displays to Biotic Regions display you saw at the Texas Memorial Museum, and describe how they are similar of different.

Stop 9: The Butler Landfill

From stop 8, return down the steps and turn east (right) when you reach the road. When you reach the Mopac (Loop 1), freeway overpass, turn left and pass through the parking area and continue down across the large gravel parking area to the Hike and Bike trail which runs near the side of Town Lake.

Between the Hike and Bike trail and Stafford Drive, the ground surface is uneven. This area was once quarried for sand and gravel, and then turned into a landfill for Austin’s municipal and household garbage. The Butler Landfill has been closed since 1968 and extends from the small pond on the east side, below a grassy area and westwards towards the banks of Eanes creek. The "fill" (fancy name for garbage) is 30 ft thick and gradually settling as the waste decomposes and compacts. You can see the amount of settling by looking at the concrete aprons on the bridge pilings. These one foot concrete aprons were added as the landfill sank to shore up the pilings as the land around it recedes. Rainwater that now settles into the depression areas and mixes with the "fill" may possibly end up in Town Lake- the lake that supplies your drinking water. Water testing and visual inspections are conducted regularly to watch for this serious hazardous pollution problem. Town Lank is especially vulnerable during rainy spells where the regular ground becomes saturated and the extra rains runoff into the nearest drainage- in this case Town Lake. Nest time we have flooding-think about what could be happening to your drinking water!

The City of Austin periodically spreads dirt over the landfill to prevent the pooling of rainwater that could percolate down and into Town Lake. The city has also built a retaining wall between this old landfill and the lake. Remediation of this site is also being considered (but it is expensive). There are many old landfills, like Butler, scattered throughout the city of Austin- and they were all operating before strict regulatory garbage disposal procedures were in place. Under modern regulations, a landfill could not exist so close to a limestone based aquifer, creek and spring system where the city garbage could so easily end up polluting the municipal water supply.

This is the end of the official self-guided tour. I recommend you continue to follow the Hike and Bike trail along Town lake and Barton creek where you can relax, get some exercise and look for wildlife such as parrots (there is a small population of wild monk parakeets) turtles and nutria along the river. You can even rent canoes on Barton Creek below the springs, or go for a ride on the miniature train (providing you are still into this sort of thing).