Barrier islands are landforms which are flat or lumpy areas of sand. It is formed by waves and tides. They usually occur in chains. It can consist from a few islands to more than a dozen. They can change during storms and other actions. The longest and widest barrier island is Padre Island of Texas.
- Garrison, J. R.; Williams, J.; Potter Miller, S.; Weber, E. T.; McMechan, G.; Zeng, X. (2010-04-01). "Ground-Penetrating Radar Study of North Padre Island: Implications for Barrier Island Internal Architecture, Model for Growth of Progradational Microtidal Barrier Islands, and Gulf of Mexico Sea-Level Cyclicity". Journal of Sedimentary Research. 80 (4): 303–319. Bibcode:2010JSedR..80..303G. doi:10.2110/jsr.2010.034. ISSN 1527-1404.