In 1851, as the first Anglo-American settlers moved into the Texas area, they started to dig wells for their homesteads. When digging such a well, early pioneer T.U. Wade discovered a rock wall and suggested that the area be named Rockwall after the peculiar geological structure. This obvious name was accepted by the townspeople and on April 17, 1854, the town of Rockwall was platted.
In the twentieth century, geologists and archaeologists studied the rock wall. They discovered that it was a jointed, natural, sandstone dike, that had intruded upon Cretaceous marlstone (a calcium carbonate mudstone that contains a mix of clays and silt) giving it an appearance of being an artificial wall.
Today, Rockwall is a city in Rockwall County, Texas, and is a suburb of Dallas, Texas, and a portion of the Dallas/Fort Worth Metroplex. The city is also the county seat of Rockwall County, and is the third wealthiest county in all of Texas.