Big Spring Plaque

Gazing at the Big Spring Plaque, one might hear whispers of ancient stories carried on the gentle breeze. This unassuming marker, nestled within the bustling city of Dallas, tells a tale far older than the city itself. Big Spring Plaque commemorates not just a natural spring, but a vital resource that has quenched the thirst of inhabitants for millennia. Big Spring, one of the few remaining natural springs within Dallas city limits, is tucked away in Pleasant Grove’s Pemberton Hill neighborhood. It’s a constant source of clear, clean water, flowing steadily year-round and discharging over twelve million gallons annually into the Trinity River watershed. The water, with its slightly acidic pH of 6.7 and low dissolved oxygen content, hints at an ancient source. Carbon dating, funded by curious citizens in 2013, confirmed this, tracing the water back to 1360 AD. Imagine the creatures who drank from this very spring centuries ago. Big Spring’s water flows into Bryan’s Slough (also known as Oak Creek), a small stream that eventually joins White Rock Creek and finally, the mighty Trinity River. Located at approximately 405 feet above sea level, the spring sits on the Trinity Terrace. This geological formation consists of Pleistocene-era gravel deposits layered over Austin Chalk, a limestone common in Dallas County. The Pleistocene epoch, marked by repeated glaciations and a much wetter climate, shaped the landscape we see today. The Trinity River, once a much larger body of water, carried vast amounts of sediment, carving out a valley that stretched from present-day Fair Park to the Dallas Zoo. These very gravel deposits, remnants of a wetter past, are believed to be the aquifer feeding Big Spring. These gravels are also a treasure trove of fossils from the Pleistocene Megafauna, with museum-quality specimens found nearby. Big Spring Plaque stands as a testament to the enduring power of nature, a quiet reminder of a time long past, persisting amidst the urban sprawl.