The Sandbar EarthCache
Hawkhaven: No longer available.
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E. G. Simmons Park is a short distance from I75 and a great place to stretch your legs and take a break. There are picnic facilities, a beach and stunning views.
Many EarthCaches are based on geological history spanning back hundreds of thousands of years. However, this lesson explores more recent history and specifically how swiftly the actions of man can be erased by Mother Nature.
Tampa Bay is Florida's largest open-water estuary, extending over 1031 square km. and forming coastlines of Hillsborough, Manatee and Pinellas counties. The freshwater sources of the Bay are distributed among over a hundred small tributaries, rather than a single river. It has been designated an estuary of national significance by the United States Environmental Protection Agency, for its fringe of mangrove and its prolific mud flats.
The bay has been a brackish estuary with a wide mouth connecting it to the Gulf of Mexico for approximately the last 6,000 years. Prior to that time, it was a large fresh water lake, possibly fed by the Floridian Aquifer through natural springs. [1] Though the exact process of the lake-to-bay transformation is not completely understood, the leading theory is that rising seas levels following the last ice age coupled with the formation of a massive sink hole near the current mouth of the bay created a connection between the lake and the gulf.
As sea levels rose and fell over Florida, the calcium carbonate remains of sea creatures and algae formed sedimentary limestone bedrock. Erosion of the limestone bedrock causes karst development. Karst is a terrain or type of topography underlain by soluble rocks, such as limestone. Given many thousands of years, this geological process results in unusual surface-subsurface features such as sinkholes.
Simmons Park - Simmons Park was created in the 1960’s by dredging and filling an area of 258 acres of mangrove swamp along the southeast shoreline of Tampa Bay. Another 200 acres of intact wetlands was donated to the County as a wildlife sanctuary.
Dredging - In the 1960’s Mangrove Point, the area that is now Simmons Park, was dredged to create a central bayou and canals for a proposed waterfront community that would feature immediate Tampa Bay access for residents. The material dredged up was used to fill an area of 258 acres of mangrove swamp. We have not been able to unearth why the project failed, but thankfully this land along with another 200 acres of intact wetlands was donated in June, 1968 to Hillsborough County as a park and wildlife sanctuary.
Much of the following material was gleaned from conversation with the park rangers.
Mangrove Point was dredged into a large, central bayou to create a maximum amount of waterfront property. This was achieved by creating a complex shore line consisting of many smaller intrusions of water, especially on the southern part of the tract. Another goal was a safe harbor for resident’s boats protected from the waves and wind action of the open gulf. One small opening (Hunter Pass) was preserved between the harbor and the gulf for access to the gulf.
Mother Nature can take a dim view of man’s land improvements and over the last 40 years she has reasserted herself. Wave action and currents floated in Mangrove tree seedlings which quickly grew and wreath the bayou. Birds and wind brought seeds for land vegetation, both native and invasive. And somehow the sandbar gradually shaped into the problem it is today. There are no records of the depth of Hunter Pass before the dredging and without that knowledge it will be difficult to get the permits today to dredge away the sandbar.
To claim credit for this EarthCache, you must meet all three of the following requirements:
1. Go to the posted coordinates and e-mail us the answers to these questions:
a. Name two invasive plant species that are the focus of eradication in this area other than Brazilian Pepper and Australian Pine.
b. Fill in the blanks. Invaded areas tend to become ______________ with greatly reduced __________ __________________.
2. Go to N 27.44.840 W 082.28.104 and you will find yourself looking at a large sandbar. On your log, post a picture of yourself and your GPS with the sandbar in the background.
3. Now for some detective work that will require you to drive around the park and draw some conclusions. Include in your e-mail your opinion of what will happen to the large central bayou over the next 50 - 100 years if the sandbar continues to grow. These questions should help you formulate your answer.
a. Where do you think the sand came from? (Clues might be observing wave currents, especially at high tide and carefully observing the north park border on Tampa Bay shore line.)
b. Walk out on the sandbar. If swimming was allowed, would you want to swim on the north or south side of the sandbar? What is the sandbar doing to the bayou to the south?
c.Ride around the central bayou. Why do you think the park service has installed culverts opening to Tampa Bay? If you are brave, sample the water. Is it salty, brackish or fresh. Do you think the water depth is increasing, decreasing or staying the same?
DO NOT post the answers to numbers 1 and 3 in your log, not even encrypted. E-mail the answers to us after you post your log.
The night we placed the cache a mother manatee and her calf were enjoying the incoming tide in Hunter Pass. We can’t promise you will see the manatees that frequent the park, but the area teams with birds and other wildlife.
THANKS TO MACDONR - FTF, HELPER & ENCOURAGER
Additional Hints
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