Origin and development of the Texas shoreline

The coastal features of Texas can be divided into four main groups on the basis of their general characteristics and origin. These are: 1) alluvial valleys and deltaic plains, 2) estuaries, 3) barrier islands, and 4) lagoons. It appears that a combination of factors, including fluctuations in sea level associated with the last Pleistocene glacial stage, the seaward slope of the late Pleistocene coastal plain, the amount and location of sediments contributed to the coastal region by Texas streams, longshore currents and waves in the Gulf of Mexico, and variations in climatic conditions from east Texas southward to the Rio Grande have led to the origin and development of the modern shoreline of Texas.