Grand Canyon Skywalk and Hoover Dam
The story of Guano Point starts a few decades ago. In the 1930s, Harold Carpenter decided to go for a boat ride down the Granite Gorge. On the ride he noticed a hole in one of the canyon walls. He estimated the hole was maybe, 600 feet above the water, and he was curious. Three days of climbing later, he finally reached the hole.
As it turned out, the hole was a giant cave and it was filled with guano. Aka bat poop. Guano is rich in nitrates and phosphates, which is a main component in fertilizer. A mining engineer even estimated that there was at least 100,000 tons of guano in the cave with an estimated value of $12-15 million, in the 1930s. That guano was gold.
Several companies attempted mining Guano Point, most of them unsuccessful.
Attempt #1: Extraction via tramway. That seemed simple enough. The plan was to build a tramway from the cave entrance to a barge dock below. The small company immediately went bankrupt from construction expenses due to barges sinking and tram motor repairs.
Attempt #2: Extraction via plane. The King-Finn Fertilizer Company pursued this, building a landing strip on one of the sandbars a little upstream from the cave. They used the tramway that had previously built to haul guano out of the cave. Then they loaded the guano onto boats in the water. The boats would then float down the river to the airstrip and the guano would then be loaded into the airplane and sent off. However, this turned out to be mega expensive and rivers – crazy enough – are prone to changing water levels which would – and did – cover the airstrip.
Attempt #3: In 1957, the U.S. Guano Corporation bought the rights to the cave and began formulating plans to extract all the guano from the cave. Their plan was to build a tram from the cave all the way to the other side of the canyon, 7,500 feet (2300 m) across at a whopping $3.5 million dollars. 30,000 feet (9100 m) of steel cable was used to haul up the cable cart from the mine.
https://en.wikipedia.org/wiki/Bat_Cave_mine
