The Texas High School Coastal Monitoring Program Field Guides
Mustang Island Field Guide - Field Stop 3

Mustang Island State Park, in Nueces County south of Port Aransas, was purchased from private owners in 1972 and opened to the public in 1979. The Park includes 3,954 acres, including 5 miles of beaches on the Gulf of Mexico. The park is covered with dunes, some up to thirty-five feet in height, and is home to a wide variety of coastal vegetation, including various grasses, shrubs, and sea oats. Tidal flats and marshy areas on the bay side of the island are characterized by salt-tolerant plants, but depressions that hold water after heavy rains also support dense growths of cattails, bullrushes, and sedges. Native animals include spotted ground squirrels, pocket gophers, grasshopper mice, rice rats, cotton rats, rabbits, opossums, raccoons, skunks, armadillos, and a small number of coyotes. Shorebirds are common, and waterfowl and other migratory birds can be observed during various seasons. For more information about the history of Mustang Island State Park, visit the Texas Parks and Wildlife Departments website: http://www.tpwd.state.tx.us/spdest/findadest/parks/mustang_island/.

To see aerial photos of Fish Pass in Mustang Island State Park, please visit: http://texascoastgeology.com/passes/fishpass.html.

In addition to the tidal currents, there are also currents that move sediment along the Gulf shore. This movement of sediment up or down the shore is called longshore drift. Because waves approach the shore at an oblique angle, the sediments mobilized by the waves are swept up or down the coast and "drift" in the direction of the waves. On Mustang Island, the direction of longshore drift tends to change with the seasons. For much of the year, low to moderate winds, and, therefore, waves typically come from a southeasterly direction, inducing gentle longshore currents and sediment transport northeasterly up the coast. However, during the winter months the strong but episodic northeasterly winds drive waves and longshore currents to the south. In an average year, the southwesterly transport of sediments by longshore drift is dominant. The jetties at Fish Pass in Mustang Island State Park are a good place to look for evidence of longshore drift. Compare the beaches adjacent to the jetties with the beach along the rest of the park.