Al Naslaa Rock Formation: How Did the Bizarre Geologic Feature Develop?

In a desert in Saudi Arabia, a geologic formation looks completely strange due to its perfectly vertical rock fissure. Due to its mysterious origin, it has become a famous tourist attraction and a common subject for various theories.

What Makes the Al Naslaa Rock Peculiar?

Located 50 km south of the Tayma Oasis in Saudi Arabia is a landform known as the Al Naslaa rock, which features a large chunk of sandstone. The rocks sit on two small natural pedestals measuring 6 meters high and 9 meters wide.

The rock sculpture features a lot of bizarre characteristics, which remain a mystery until today. First, the rock is divided in the middle by a perfectly straight gap which seemed impossible to be done by ancient humans. The way the rocks are connected to the pedestals also appears to be floating in perfect balance.

Moreover, the side of the rock facing southeast is filled with numerous petroglyphs or rock engraving which depicts Arabian horses, humans, and ibexes. These petroglyphs are thought to be at least 4,000 years old, suggesting the presence of human inhabitants who thrived during the Bronze Age.

Possible Causes of the Strange Rock Formation

Several theories on how the perfect split was formed perfectly down the middle of the boulder. One suggestion is that the rocks sit directly above a fault line, and the shifting of the ground beneath them causes them to split in half. It could also be that the crack is a joint which, in geology, refers to a brittle-fracture surface in rocks that are formed without displacement. Just like in Al Naslaa rock, most of the joints move toward the vertical rather than the horizontal direction.

Another theory is freeze-thaw weathering, where water seeped into the cracks of the then-single sandstone rock. As the water got frozen, it expanded and exaggerated the small cracks. Upon thawing, the ice melted and left behind a perfectly straight division.

Some also believe that the crack initially served as a tunnel for sand-laden wind, which glides across the landscape. As the grains of sand passed through the gap for thousands of years, they polished the uneven crack, forming a perfectly smooth surface.

Since the Al Naslaa rock formation is made from sandstone, it is not impossible to suggest that the cracks are man-made. Shearing the rock down the center can be easily done using simple metal tools, although to motive for doing such an arduous task of chopping a large rock in half will remain a mystery. Some suggest that ancient civilizations may have created the rock formation as a form of art, a geographical landmark, or a religious site.

The terrestrial features possessed by Al Naslaa rock can also be found in many parts of the world. In the U.S., the Balanced Rock located in Arches National Park displays the same unstable equilibrium formation. Similar natural wonders can be seen in Egypt's White Desert, where massive boulders sit above a thin pedestal. Meanwhile, the Split Apple Rock in New Zealand features granite with an almost perfect split caused by a naturally occurring joint.