White Rock Creek rises two miles southeast of Frisco in southwestern Collin County (at 33°08' N, 96°47' W). Intermittent in its upper reaches, the creek follows a southerly course for 23½ miles into White Rock Lake. After the lake it continues south for another eight miles to its mouth on the Trinity River, two miles southeast of where the Interstate Highway 45 crosses the Trinity in Dallas (at 32°43' N, 96°44' W). The bed of the creek is composed predominantly of Austin chalk, which weathers, upon exposure, to a tan-white color. Some of the earliest settlements in Dallas County were on the creek, which was known as White Rock Creek by 1844, when the National Road of the Republic of Texas was surveyed across it. Although the creek for most of its course lies within the city of Dallas, the natural vegetation along its bank is undisturbed in many areas, which are generally heavily wooded, mainly with cedar elm, pecan, and ash.