A Journey through Geological Time and the Chassahowitka River

When I first started this essay I thought I would have to throw out all my research and find some other geological formation in Florida. But then I stumbled upon something very interesting. Before I found this I was trying to figure out how to connect a spring to a geological rock formation. My mentor advised to change my topic. But then I found out springs and sinkholes are formed from karst formations. This indeed is a geological feature and thus I bring you the Chassahowitka spring complex. To see a few of the rocks the I collected from the karst (spring) view images R.1 through R.7

For this assignment I have deiced to explore the wild and wonderful Chasshowitkz spring complex. I choose to explore this geological feature because this river contains at least six different springs and is located in a swamp. I never thought I would find a spring in a swamp let alone so many.

History 101

Before we get in over our heads, lets take a look at the history of this area. The Springs in the Chassahowitka river produce several gallons of water each day causing the river to flow. People and animals have depended on this flow for hundreds of years. Indians use to hunt, fish and gather wild plants all thorugh this area. Evidence has been found that suggest that they had several different campsites in this region. Within the swamp is an island called Indian Bend. This island is a burial mound. Check stamped pottery as also been found on the island.

No evidence has been found, but Seminole Indians were believed to have been in the area during the Second Seminole War. They are the ones who named the swamp Chassahowitzka, which means pumpkin hanging place. They were referring to a small climbing plant that is now extinct.

Toward the end of the Civil War, many families hiding from the aftermath settled on tiny island all through the river. Each island had a kitchen, livestock, gardens and trees for food. The islands received their names from the family occupying them. Some islands had schools built on them. Settlers made there homes out of palm logs with palm leaf roofs.

In the 1900's bald cypress and red cedar was harvested to make cigar boxes and pencils. Tram systems were created for mules to hail wood from the swamp to the railroad. Many of these systems remain today and are used by hunters.

A small logging town developed in 1910 to 1922. The town was called Centralia. The population of Centralia was around 1500. The town had a school , doctor and dentist. The town was made up of all kinds of different ethnic groups. But in the late 1930's the railroad ceased operation and the town became a ghost town.

"In 1985 land for Chassahowitzka was purchased from the Lykes Brothers and the Turner Corporation as part of Florida's Conservation and Recreation Lands (CARL) program. " (State of Florida, 1999). As you can see this area has been through many developmental changes, but from a quick glance it just looks like a swamp with a river flowing through it. I can only images Indians and other people gathering drinking water from the spring or maybe canoeing down the river. But how did these springs come to be?

Swimming in the Spring

Chassahowitzka is a coastal spring complex, formed when a karst flooded ; form spring vents, fissures, and highly-eroded limestone at or near land surface. If you look at image S.1 you can kind of make out the opening in the ground. Image S.2 though S.4 are images of the inside of the spring. Springs and sinkholes are created by water and carbon. When it rains the water collets carbon from the earths atmosphere. Once the rain hits the ground, it moves through the soil and gathers more carbon. It then forms a carbonic acid solution: H2O + CO2. The water then moves through fractures and cracks in the limestone. Over a period of time these crakes and fractures become larger. This then allows more water to pass through the fractures that then contributes to there growth. Physical erosion washes away rock and sand. This is what makes a cave larger and forms an underground stream. In this case a sinkhole was formed. The sinkhole then begins to regenerate or produce water.

Limestone

But what is limestone? Limestone is as known as calcium carbonate. "As all the tiny sea creatures die, they sink to the bottom and their bodies build up on the sea floor. Limestone is basically the fossilized and calcified remnants of these creatures. Geologically speaking, Florida limestone is very new. It is only 50-60 million years old. Florida limestone is very soft, very white, and contains many fossils. Central Florida limestone is known as the Ocala Group" ( Unknown, n.d.).

The Chassahowitzka happens to be in the area were the Ocala Uplift occurs. The layer of clay known as Hawthorn Formation is very thin in this area. The Hawthorn Formation keeps water from getting in and it keeps water from getting out. The area were the Ocala Uplift is located is also a major zone for the aquifer to recharge in. The whole state of Florida is venerable to karst activity as you can see in image 1.d. This image show that karst activity is more abundant in some area.

What in Karst?

Karst can be defined as an area of abnormal limestone in which erosion has produced fissures, sinkholes, underground streams, and caverns. Karst are very common near the Florida aquifer system. "Karst processes characteristically develop zones of enhanced porosity within carbonate rocks creating a highly heterogeneous aquifer system with rapid rates of ground-water movement and recharge. Subsidence events caused by the collapse of materials into overlying caverns and caves can result in structural damage at land surface" (Tihansky, 2002). If you look at image 1.5 you can see how ground water can easily reach the Florida aquifer. Image 1.8 show how karst formations can effect rivers lakes and streams.

The spring complex within the Chassahowitzka river were initially formed as sinkholes. These sinkholes just happen to be in a recharge region where acidic waters were under saturated with regard to calcite. There are three kinds of vents with in the spring complex. These are linear fracture, circular rock vent , and sediment filled vent. You can even see the sand boil in some spots. "The types of vents that form usually reflect characteristics of the rock. Hard, brittle zones in limestone units maintain larger openings such as caverns and fractures while softer limestone collapse more readily" (Tihansky, 2002).

Big Bubba

The Chassahowitka spring complex is located along the Chassahowitka river in western Citrus county in Florida. The springs are located all through the river, but I will be focusing on the cave formation of the springs that is located at latitude 28 42' N 58.24" and longitude 82 34' W 30.32". The caves are located in bedrock limestone. The measurement of the pool is 69 feet north to south and 81 feet east to west. There are two small spaces in which the water flow moves. The depth of the water over the vent is 8.3 feet. The water is clear and the area is heavily wooded. Most of the limestone is coved with algae.

The spring that I am focuses on is called spring number one or Bubba springs. It is made up of several small springs or karst that connect to each other. It is the largest and shallowest spring in the complex. Bubba springs is circular rock vent. It is comprised of two vertical pipes connected by a 15-foot horizontal conduit. The flow from Bubba Spring comes from a small opening in the parallel passage, midway between the two vertical pipes.

The water found in this area is fresh enough to drink, however this area has experienced some contamination from septic tank leeks. I also found that the county has know about the pollution in the river and they have done nothing to notify the public. The county has also been involved in a major lawsuit because they have done nothing to protect this area or the wildlife refuge that surrounds it. Several documents stating all the volitions in detail can be found at http://www.welovechaz.com/CRRC/CRCC%20Report.htm.

A lady never tells her age

From my investigation I collected four rocks which can be viewed be opening images R.1 through R.4. In order to determine what kind of rock I had I used two maps that can be seen in images M1. and M.2. The first thing that I noticed about the rocks is that they seemed to be falling apart in my hand. Every time I would set one down little pieces would fall of here and there. I also noticed that for the most part the rocks were covered with green grassy algae. This is most likely from the mineral and nutrients in the water. A table of nutrients and minerals that have been found in a water sample from this area can be seen in image T.1. I also noticed many fossil in the limestone. I noticed the back side of R.5 (2.) is a dark brown color not white. This is from impurities that become stuck in the structure during formation. I also noticed that this rock seems to be very prose. It had thousands of small holes all through it. It is often very difficult to date the age of a cave. Because the upper part is usually older. A general rule of thumb is the larger the cave the older it is.

So my oldest layer has algae growing all over and as I move down the rock I can see imprints of sea shells and snails. This leads me to believe that formation took place sometime between 245-545 million years ago. I say this because from my research these shells are called Mollusks. "Mollusks first appear in the fossil record about 545 million years ago in earliest Cambrian time, but the record of their origin and early evolution has not been discovered in the fossil record. By late Cambrian time most of the modern groups of mollusks can be found in some primitive form as fossils occurring in marine deposits. During the Ordovician a major radiation of mollusks occurred, with thousands of species of mollusks appearing in the fossil record of that time" ( USGS,1999).

"During the period covered by this proposal a method for the direct determination of ground-water ages and flow rates was developed based on the carbon-14 content of the dissolved carbonate species in the ground water system. Most of the C14 content of the dissolved carbonate species in ground water comes from the soil-zone CO2 and is derived principally from the oxidation of organic matter within this zone. Dissolved carbonate species within the ground water may come from the CO2 of the soil-zone and also from solution of limestone in the aquifer; in some cases magmatic, petroleum- or plant-derived CO2 may be introduced into the aquifer also. Soil-zone CO2 is derived from plant respiration and decay and its carbon isotope composition should be equivalent to that of plants. Marine limestone from the aquifer will contain no carbon-14 because of its age and will dilute the datable, soil-zone-derived carbon. To determine true age of ground water the measured carbon-14 content must be corrected for this solution of limestone and dilution of carbon-14" (Hanshaw, 1969).

Before absolute dating relative dating was used to determine the age of rocks. Geologist use the study of fossils and structural combination. To use this method we need to look at the layers in the rock and the different fossil in each layer. Relative dating has four basic principles, the Principle of Original Horizontality, the Principle of Lateral Continuity, the Principle of Superposition and the Principle of Faunal Succession.

The Principle of Original Horizontality say that when sediments fall to the earth's surfaces they fall in a horizontal matter. This means that when we find samples that are not horizontal tilted or fooled after they were already deposited. The Principle of Lateral Continuity says that geologist can relate or compare layers of sediment from one location to another location that may be thousands of miles away. The Principle of Superposition says that older layers of sediment are always underneath the newer layer and if the older layer is not below the newer layer; then this has been caused from the shifting of the earths crust. "The principle of faunal succession holds that sedimentary rock strata are observed to contain fossilizedflora and fauna, and that these fossil forms succeed each other in a specific, reliable order that can be identified over wide distances. A fossilized Neanderthal bone will never be found in the same stratum as a fossilized Megalosaurus, for example, because the two species lived during different geological periods, separated by many millions of years. This allows for strata to be identified and dated by the fossils found within them" (Principle of faunal succession, n.d.).

Transformation

A major principle used by geologist is Minerals and rocks are stable only under the conditions at which they form. Change the conditions and the rocks will change to adapt to the new conditions. Limestone comes from shell, coral and other dead organisms. It is sedimentary rock formed by the breakdown of other rocks or shells. The process of a rock changing into another type of rock is called the rock cycle. As image 7.7 " illustrates, each type of rock is altered or destroyed when it is forced out of its equilibrium conditions. An igneous rock such as basalt may break down and dissolve when exposed to the atmosphere, or melt as it is subducted under a continent. Due to the driving forces of the rock cycle, plate tectonics and the water cycle, rocks do not remain in equilibrium and are forced to change as they encounter new environments. The rock cycle is an illustration that explains how the 3 rock types are related to each other and how processes change from one type to another over time" (Wikipedia, 2007).

Weather and its changes

Limestone is an example of a sedimentary rock, which has not formed from the processes of weathering. So that counts weather out or does it? The weather may have affected the current and moved shells and other organisms around. For example the wind controls the current . That may explain why limestone is thicker in some area than another. Water has had a radius effect here, because water is what formed the karst.

Like I stated earlier acidic rain moves through wholes in the rock making them bigger until we end up with a spring or sinkhole. The wind and hurricanes sometimes also come through and destroy the area, ripping up vegetation and braking trees in half. I visited this area once after a hurricane and the water was very dark and gloomy, rather than its glowing blue color. I assume that this is from run off and sediments being moved around.

As for ice we don't really see much of that in this area. But in the winter we do sometimes have a forest or a storm that causes a freeze. This can cause vegetation in the area to die. However, winter in other locations also have an effect on this area. This is because that many fish, bird and matinees migrate to this area in the winter. This causes the population in this area to grow and with less vegetation this can lead to a food shortage.

Conclusion

When I started this investigation I had no clue that Florida had some many fascinating

geological features. I had never heard of a karst. But now that I have discovered them, I would like the chance to investigate them further. It's remarkable to think that something as simple as rain can cause a hole in the ground and that, the same rain fills the aquifer and can recharge the hole and make a spring.

References

Hanshaw, B. (1969). The Evaluation and Applications of C14 Dating of Ground Water. Retrieved July 21, 2007, from National Technical Information Service. Web site:http://stinet.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identif yyyie r=AD0690265

State of Florida, (1999). Chassahowitzka Wildlife Management Area. Retrieved July 15, 2007, from Florida Fish and wildlife Conservation Commission Web site: http://myfwc.com/recreation/chassahowitzka/history.asp

Tihansky, A. (2002, March). Karst Features and Hydrogeology in West-central Florida -- A Field Perspective. Retrieved July 15, 2007, from USGS Web site: http://water.usgs.gov/ogw/karst/kigconference/abt_karstfeatures.htm

Principle of faunal succession. (n.d.). Wikipedia. Retrieved July 28, 2007, from Answers.com Web site: http://www.answers.com/topic/principle-of-faunal- succession

Unknown, (n.d.). Basic Central Florida Geology. Retrieved July 15, 2007, from FSS Web site: http://www.caves.com/fss/pages/misc/geoflorida.htm

USGS, (1999). Mollusks. Retrieved July 28, 2007, from USGS Web site: http://geology.er.usgs.gov/paleo/mollusks.shtml

Wikipedia, (2007). Rock (geology). Retrieved July 28, 2007, from Wikipedia Web site: http://en.wikipedia.org/wiki/Rock_(geology) : This essay will take you to an often unexplored world. You will enter a beautiful clear blue glowing spring and follow it to the Florida Aquifer to discover how it was created.