The famous prehistoric site Stonehenge has been a mystery to scientists for centuries. The puzzling structure is composed of dozens of huge, heavy stones arranged in a semi-circle. Archaeologists have long wondered whether the structure was originally a complete circle. Now, after a season of dry weather, they finally have a clue.
Every summer at Stonehenge, groundskeepers water the surrounding land to keep the grass moist and healthy. But this year, the hose the groundskeepers used was too short to reach the entire site! This meant that a small area of the monument was left to dry out in the summer heat.
This dry patch of ground eventually began to show some interesting marks, which looked like the outlines of underground stones. Stones, buildings, and other monuments buried deep in the ground can affect the growth of the grass that sits above them, even thousands of years after they were covered over. Experts at Stonehenge realized that the “parch marks” were revealing a hidden segment of Stonehenge to them. These underground archaeological features appear to complete the inner circle of Stonehenge—just as scientists have long suspected!
There are still many mysteries surrounding Stonehenge and its creation. Archaeologists have many theories about why the monument was built. Some think the site could have been a religious temple, while others think it served as a graveyard.
The only thing scientists know for sure is that the monument was built close to 5,000 years ago. Most also agree that astronomy, the study of stars, played an important part in the planning of the site. The stones seem to have been carefully placed to line up with the sun on the winter solstice (the shortest day of the year) and the summer solstice (the longest day of the year).
More perplexing is the question of how prehistoric peoples were able to construct Stonehenge, at all. Some of Stonehenge’s largest rocks are as tall as 30 feet high, weigh as much as 30 short-tons, and were dug out of the ground as far as 30 miles away from the site!
There are approximately 2,205 pounds in a metric ton, and 0.9 metric tons in a short-ton. About how many pounds would a 30 short-ton stone weigh?