Jacob's Well is a perennial karstic spring in the Texas Hill Country flowing from the bed of Cypress Creek, located northwest of Wimberley, Texas. The twelve foot (four meter) diameter mouth of the spring serves as a popular swimming spot for the local land owners whose properties adjoin Cypress Creek. From the opening in the creek bed, Jacob's Well cave descends vertically for about thirty feet (ten meters), then continues downward at an angle through a series of silted chambers separated by narrow restrictions, finally reaching a depth of one hundred and twenty feet (forty meters). Until the modern era, the Trinity Aquifer-fed natural artesian spring gushed water from the mouth of the cave, with a measured flow in 1924 of one hundred and seventy gallons per second (six hundred and forty liters per second) discharging six feet (two meters) into the air. The spring is the greatest source of water recharging the Edwards Aquifer.

Afghan artists perform a re-enactment of the lynching of Farkhunda, a 27-year old woman, to protest against her killing in Kabul, April 27, 2015. Farkhunda, who was killed by an angry mob in front of police in the Afghan capital in March for allegedly burning a copy of Islam's holy book was wrongly accused, Afghanistan's top criminal investigator said on March 22. The killing has fuelled anger about the weak rule of law and corruption that is crippling the country's instutitions. (Photo by Omar Sobhani/Reuters)

In this Monday, April 27, 2015 photo, a Nepalese man walks over fallen rocks and past a crushed car on the way to Dhunche, Nepal, a village in Langtang National Park, two days after a 7.8-magnatude earthquake hit the region. The photographer, Joe Sieder, said the man was part of a group of Nepalese workers and trekkers who left Syabrubesi earlier that day and hiked about 30 km (19 miles) for 13 hours, mostly over boulder-strewn roads with some small landslides along the way to make their way to a passable road. (Photo by Joe Sieder via AP Photo)

NASA's Cassini spacecraft has provided scientists the first close-up, visible-light views of a behemoth hurricane swirling around Saturn's north pole. In high-resolution pictures and video, scientists see the hurricane's eye is about 1,250 miles (2,000 kilometers) wide, 20 times larger than the average hurricane eye on Earth. Thin, bright clouds at the outer edge of the hurricane are traveling 330 mph(150 meters per second). The hurricane swirls inside a large, mysterious, six-sided weather pattern known as the hexagon. Photo: The spinning vortex of Saturn's north polar storm resembles a deep red rose of giant proportions surrounded by green foliage in this false-color image from NASA's Cassini spacecraft. (Photo by NASA/JPL-Caltech/SSI)

“Sally Mann (born in Lexington, Virginia, 1951) is one of America’s most renowned photographers. She has received numerous awards, including NEA, NEH, and Guggenheim Foundation grants, and her work is held by major institutions internationally. Her many books include Second Sight (1983), At Twelve (1988), Immediate Family (1992), Still Time (1994), What Remains (2003), Deep South (2005), Proud Flesh (2009), and The Flesh and the Spirit (2010). A feature film about her work, What Remains, debuted to critical acclaim in 2006. Mann is represented by Gagosian Gallery, New York. She lives in Virginia”.

Photo: Candy Cigarette, 1989. (Photo by Sally Mann)

Merit: A Night at Deadvlei. The night before returning to Windhoek, we spent several hours at Deadveli. The moon was bright enough to illuminate the sand dunes in the distance, but the skies were still dark enough to clearly see the milky way and magellanic clouds. Deadveli means “dead marsh. The camelthorn trees are believed to be about 900 years old, but have not decomposed because the environment is so dry. (Photo and caption by Beth McCarley/National Geographic Traveler Photo Contest)

An employee of Paris city Hall removes padlocks clipped by lovers on the fence of the Pont des Arts over the River Seine in Paris, December 9, 2014. For years, visiting couples have hung brass padlocks on the iron grills lining the city's bridges to symbolise their undying love – they write their names on the locks, then toss the key into the Seine below. About 700,000 love locks are added every few months and Paris officials say they are damaging the bridges and threatening safety because of the added weight. (Photo by Philippe Wojazer/Reuters)

In this December 29, 2004 file photo, Kusol Wetchakul offers prayers for the soul of his sister, at dawn along the beach near Khao Lak, Thailand. Wetchakul's sister was swept out to sea and believed drowned as she sold goods to tourists on the popular tourist beach just north of Phuket. Friday marks the 10th anniversary of one of the deadliest natural disasters in world history: a tsunami, triggered by a massive earthquake off the Indonesian coast, leaving more than 230,000 people dead in 14 countries and causing about $10 billion in damage. (Photo by David Longstreath/AP Photo)