The refuge includes several Gulf of Mexico coastal habitats, such as saltwater marshes, islands, tidal creeks, and the estuaries of seven north Florida rivers. It is home to a diverse range of plant and animal life and also has a long history of human use, including structures such as the St. Marks Lighthouse, the second oldest lighthouse in Florida.
Hours of operation:
The refuge is open year 'round, daylight hours. The Visitor Center is open Mondays - Fridays, 8am – 4 pm; Saturdays and Sundays, 10 am – 5 pm; Closed most Federal holidays.
Pets on a leash are allowed on the refuge.
Fees, Costs, and Rates : A $5/car entrance fee is collected at the St. Marks Unit of the National Wildlife Refuge.
Contact the refuge: Telephone: (850)925-6121 Email Address: saintmarks@fws.gov
To the uninitiated, Florida seems like a flat place devoid of geologic features. However, this is not exactly true. Florida landscapes lack the vistas of the mountains, but do have seascapes, beaches and coastal marshes. The area of St. Marks National Wildlife Refuge is a case in point. It has a relatively flat topography, but inches count in Florida. As you travel through the refuge you will see the dramatic change from pine forest to coastal marsh. This area of Florida has been underwater and exposed many times over the past three million years, as a result of fluctuating glaciers in the north. During the coldest period, about 20,000 years ago, when the ice sheets extended the farthest south, the continental shelf was exposed to a depth of 394 feet (120 meters) below the present sea level. At that time, the coastline in this area would have extended approximately 300 miles into the Gulf of Mexico. During the warmest period, approximately 3 million years ago, when the glaciers had receded to their minimum level, any land in Florida below 115 feet (35 meters) above the current sea level would have been submerged by the sea. The remaining elevated portions of the Florida peninsula became small islands during this period and provided refuge for plants and animals. As you travel from the entrance gate at the refuge to the termination of the road at the St. Mark’s Lighthouse, the change in vegetation is striking. The trees at the entrance to the refuge are growing on small remnant dunes from the glacial seas. The marshes are located in the swales or valleys between the ancient dunes. A few inches change in elevation results in trees or marsh grasses. Between 1934 and the early ‘40’s, men from the Civilian Conservation Corps literally built the Refuge. With little heavy equipment, they relied on shovels and sheer muscle to build the earthen levees surrounding the refuge ponds. These levees maintain the fresh water integrity of the ponds and prevent salt water intrusion. These fresh water ponds are vital habitat for migratory bird populations. The rocky substrate in the refuge is sedimentary rock. This means it was formed as a result of deposits and not volcanic activity. In Florida, this means the actions of the seas as they rose and fell during glacial events (ice ages). The underlying bedrock is dolomitic limestone which is the result of compression of many small mollusks (including clams and oysters) over the millenniums. These rocks are mostly white with gray tints and are near the surface in the St. Marks area. There has been mining to the north of the refuge to supply substrate for road building. The St. Marks National Wildlife Refuge is located in the “Big Bend” area of Florida. At the end of the road in the refuge, you will see a coastal shoreline. Florida is renowned for sandy beaches, but this beach is quite different. This area of Florida has a “low energy coast line.” Low energy refers to wave height. Low energy coasts are characterized by grassy marshes. High energy beaches are made by big waves that can transport sand. The waves carry sand causing dunes to build up over time. These dunes are seen on Florida’s East Coast and also along beaches in the Florida Panhandle. The beach dunes in the panhandle are comprised of snow white silica and can be 20-30 meters in height. No such dunes are found in this area of Florida. Although this beach is a low energy coast line, there have been hurricanes and severe storms which have resulted in significant storm surges in this area.
To claim this Earthcache, please e-mail the answers to the following questions to me. Please do not post the answers with your log, or include any spoilers in your log.
- 1. At coordinates N30 09.091 W084 08.889 there is posted information about a former town at this site.What was the name of the town and why did it disappear? What is the elevation at this sign? (If your GPS does not have elevation data, several free cell phone apps are available).
- At coordinates N30 07.760 W084 08.771 what is the elevation?
- At coordinates N30 04.446 W084 10.779: at the lighthouse plaque- when and why was the lighthouse moved? What is the elevation at this plaque?
The Refuge managers would appreciate information posted to your public log, including the number of people in your party, where you are from, and if you visited the Refuge specifically because of the Earthcache. Please post photos on your log, but do not include spoilers.
References:
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Wikipedia “St. Marks National Wildlife Refuge”
2. U.S. Fish and Wildlife Service Website “St. Marks National Wildlife Refuge”
3. Atlas of Florida's Natural Heritage, Florida Natural Areas Inventory, by the Institute of Science and Public Affairs, Florida State University, 2011.