San Pedro Springs Park EarthCache
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San Pedro Springs Park
San Pedro Springs Park is located about 1.6 miles north of downtown San Antonio and the Alamo. It is the oldest park in Texas and the second oldest in the United States. The park comprises forty-six acres of land and contains 13 primary springs. The springs were named by Father Isidro Félix de Espinosa, a Spanish missionary in 1709, but many scholars believe Alvar Nunez Cabeza de Vaca first discovered the site in 1535, making the springs one of the oldest historical sites in North America. In 1718, another Spanish missionary, Antonio de San Buenaventura y Olivares, built a mission nearby that he named San Antonio de Valero. The mission grew into a settlement and became known as San Antonio.
These springs are fed by water by the Edwards Aquifer which reaches the surface through faults along the Balcones Escarpment. This fault zone runs from the southwest part of the state near Del Rio to the north central region near Waco along Interstate 35. The exposed limestone on the surface of the Balcones Fault Zone is known as “Karst”. This term describes a distinctive topography that indicates dissolution (also called chemical solution) of underlying soluble rocks by surface water or ground water. Although commonly associated with carbonate rocks like limestone and dolomite other highly soluble rocks such as gypsum and rock salt can also be sculpted into karst terrain. It typically features numerous caves, sinkholes, faults and fractures where rain fall and creek and stream flows can enter the underground springs.
The “Karst” limestone found here make these springs unique. Although a karst type of stone is not uncommon, the age and the porosity of the stone found here is unusual. The karst here is approximately 15 million years old. As water has coursed its way through the underground aquifer for millions of years, the water has eroded the limestone to create significant flow channels. These open channels allow water to move through the aquifer very rapidly and only minimally filter the water. Studies in which non-toxic dye is injected into the aquifer have revealed that the water here can move up to 8 miles per day underground. This is much faster than the more common sandstone aquifers or the younger limestone aquifers found throughout most of the United States where water often moves only a few centimeters per year. This unique geology means the San Pedro and other nearby springs and the Edwards Aquifer in general is more vulnerable to pollution than any other major aquifer in the United States. Or in simplified term, if pollutants are allowed to enter the Edwards Aquifer, they will not be naturally filtered before the water emerges at the springs (or in people's drinking water wells.)
Today, because of the amount of water drawn from the aquifer, many of the nearby springs seldom flow. And even these may stop during times of drought. The springs emerge from the ground at an elevation of about 663' through a fault at the base of a limestone bluff. At the surface, Austin chalk limestone is present on the southeast side of the fault and Pecan Gap chalk on the northwest.
The springs have long been a favorite meeting place and campsite for Native Americans. Paleo-Indian projectile points and other stone tool artifacts have been found here that are more than 12,000 years old. The bones of mastodons, giant tigers, dire wolves, Colombian elephants, and extinct horses have also been found here.
Sources: (htt (visit link)
To log this EarthCache, E-mail me the answers to the following questions:
1. Describe the appearance of the Edwards Limestone surrounding the area where the springs discharge from the earth.
2. Because the water flows through the limestone here so quickly, the force of the flow varies with the day to day weather. Describe how strongly the springs appeared to be flowing during your visit.
3. Depending upon when you visit the springs, the clarity of the water can vary, it is normally clearer in the dry season and more cloudy during the rainy season. Describe the appearance of the water flowing from the springs during your visit.
The park is open from 5 a.m. – 11 p.m. daily. There are a number of geocaches located throughout the park. Please remember to stay safe and obey the park rules. Remember, Keep it Clean! If you hauled it in then haul it back out (and take a little extra with you).
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