near the top of Sour Spring Mound. The well was spudded on 27 October 1900. At , they hit the quicksands that had stopped earlier efforts. A solution consisted of driving an eight-inch casing pipe through the sand over the next 20 days, with a four-inch "wash pipe" to flush out the sand from the bottom of the hole with water. At around , Lucas improvised a check valve to prevent the increased gas pressure from forcing sand into the casing, enabling them to reach a depth of , and past the thick quicksand formation. At a depth of , they adopted eighteen-hour shifts for continuous operations, drilling during the day, and keeping circulation going at night, to prevent a gas blowout. In early December, they hit a pocket of coarse water sand, when they adopted another innovation, mixing mud into the water which prevented the "heavier" water from dissipating into the sand. This drilling mud stabilized the hole, and soon they were drilling into a clay formation called gumbo. At they reached limestone, and on 9 December, oil started showing up in the slush pit. The oil was coming from a thick oil sand at a depth of . Yet, that oil sand was too soft and fine to develop at that time, and Caroline Lucas convinced Galey to continue drilling to , per contract. On Christmas Eve, they landed six-inch pipe below the sand at , then enjoyed the holiday, returning New Year's Day. They hit another gas pocket, which forced water and mud out of the hole for ten minutes. Then, at , they reached a sulphur layer, followed by more layers of limestone. On 10 January, they needed to replace the dull fishtail drill bit. While lowering the pipe down the hole, they only got to about 35 joints of pipe, or about , before a low rumble sent mud, and then drill stem out of the hole. This was followed by silence, an explosion of more mud and gas, more silence, a flow of oil, and then a loud roar. On January 10, 1901, at a depth of 1,139 ft (347 m), what is known as the Lucas Gusher or the Lucas Geyser blew oil over in the air at a rate of (4,200,000 gallons). Nine days passed before the well was brought under control using a Christmas Tree devised by the Hamills. By late