Why Were the Stone Spheres of Costa Rica Made?
The most difficult question to answer is why the stones were made. What was their purpose? No one knows for sure, but a few theories have developed. For example, some believe they were used as compasses or to align with astronomical phenomena. Others think they were used as grave markers or status symbols, marking the property of ancient leaders.
In the early 1930s, the United Fruit Company began searching for new land for a banana plantation. They found a prime location in the Diquis Valley, which is located in western Costa Rica near the Pacific Ocean.
As workers began clearing the dense jungle lands to make them suitable for planting, they discovered something strange: stone spheres. Some were only a few inches in diameter. Some of the spheres were huge, though. The largest spheres measured as much as seven feet in diameter and weighed 16 tons.
Where in the world did these spheres come from? Or did they even come from this world? All sorts of speculation began amongst locals and many different myths developed to explain the stone spheres. For example, some believed they were brought to Earth by aliens, while others think they are somehow connected with the myth of the lost continent of Atlantis.
Scientific study of the stones began in the late 1930s and early 1940s. Despite the fact that the stones appeared to be extremely smooth and almost perfectly round, archeologists concluded that the stones were most likely handmade by ancient people indigenous to the Diquis Valley.
To date, approximately 300 of the stone spheres have been found in several locations across Costa Rica. Upon closer examination, many of the stones are not perfectly round. However, many of them are surprisingly smooth and scientific measurements show that many of them are about 96% perfect.
Most of the stone spheres were sculpted from granodiorite, which is a very hard igneous rock similar to granite. Scientists believe ancient peoples likely chose large boulders that were already somewhat round and then carefully shaped them using smaller rocks of the same material as tools. They also think that ancient sculptors may have heated portions of the stones followed by rapid cooling to remove outer layers of rock.
Many of the stones still contain marks from the tools used to shape them. The smoothness of the surfaces was probably achieved by polishing the finished stones with sand or leather. Scientists haven’t been able to pin down the exact time when they were made, but estimates range from as early as 200 B.C. to as late as the 1500s when the Spanish first arrived.