While you might think of boulders as massive chunks of rock more likely to crush you than double as a bowling ball, in geology, a boulder is simply said to be a rock whose grain size is bigger than 10 inches. Boulders are shaped by the elements and often form over millions of years, perhaps deep under the Earth’s crust or on prehistoric ocean beds.
Yet however they were formed, whether as a result of glaciers, volcanoes or other natural forces, there’s something about boulders that commands our attention – particularly when there are many of them grouped together. And be they surrounded by surging ocean waves, or standing solitary in the middle of a desert, these rocky landscapes provide some stunning images. Here are seven amazing boulder-strewn settings that we found especially beautiful.
7. Porth Nanven, Cornwall, UK
At Porth Nanven Beach in Cornwall, England, a multitude of boulders are lapped by waves. They lie strewn along the shoreline – but also sit high on the cliffs above. The boulders have a smooth oval shape, which has given rise to the nickname ‘Dinosaur Egg Beach’. If they were dinosaur eggs, they would have had to have come from many different species, because the dimensions of the rocks vary from over three feet long to about the size of a chicken’s egg.
Although these rounded rocks are of course not really the product of long-gone reptiles, their true origins are just as interesting. About 120,000 years ago, these boulders were rolled into shape by ancient seas and deposited along the shore. At the time, melting ice sheets caused sea levels to be much higher than they are today, which explains why these huge stones are also perched on top of the cliffs and not just spread along the beach.
Image: Philip Eaglesfield
As the sea levels dropped again, they left behind what is known as a ‘raised beach’, or ‘marine terrace’ – that is, one higher than the level of the present shoreline. This ancient raised beach is included in the Aire Point To Carrick Du Site of Special Scientific Interest (SSSI). It’s also a protected site and a wonderful place to explore.
Image: Tony Le
6. Bowling Ball Beach, California, USA
The round rocks of Bowling Ball Beach in California are scattered around as though they escaped from a giant’s bag of marbles. These spherical formations are more uniform than the boulders of Porth Nanven. They’re much older as well – estimated to date back 100 million years.
Technically, the ‘bowling balls’ are known as ‘concretions’. They formed under great pressure at the bottom of a deep ocean, compacting into concentric layers of hard yellow sandstone. Over time, that ocean floor, which is part of the Pacific Plate, turned into seaside cliffs. And the cliffs, which are made of softer sandstone than the concretions, have gradually eroded and released the round boulders, which drop to the beach.
Before modern geology, spherical concretions like these inspired great curiosity. People supposed them to be a variety of things, from dinosaur eggs and fossils to extraterrestrial debris. They were even mistaken for man-made objects – how else could such perfect shapes be achieved? Of course, now that we know the truth, we can admire them for the astonishing products of Mother Nature that they really are.
Image: Ingo Oland
5. Karlu Karlu, Northern Territory, Australia
Karlu Karlu, the boulder-filled desert landscape in Australia’s Northern Territory, is also known as the ‘Devil’s Marbles Conservation Reserve’. According to local Aboriginal mythology, the rounded boulders were created when a devil man called Arrange strolled through the area making a traditional hair belt (as worn by initiated Aboriginal men). Clumps of hair are said to have fallen to the ground, where they turned into the Karlu Karlu boulders we see today.
Image: Benjamin Jakabek
It’s also said that on his way back Arrange spat on the ground and that his spit became the granite boulders in the middle of the reserve. Seeing these impressive boulders and some of the astonishing angles at which they’re perched, it’s not hard to understand why people believed some more mystical forces were at work.
Image: Paul Grey
The geological explanation is that these ‘marbles’ are actually granite, formed millions of years ago by solidifying magma under the Earth’s crust. Erosion of the top layer of sandstone and the movement of the crust led to the granite breaking up and making its way to the surface. Here, the blocks were gradually weathered by wind and rain over many thousands of years, which shaped them into their present spherical formations.
4. Moeraki Boulders, Canterbury, New Zealand
The boulders of Moeraki, on the Otago coast of New Zealand, are remarkable for at least two reasons. First, they are almost all spherical in shape. And second, they come in two distinct sizes: big (1.6 to 3.3 feet in diameter) and very big (5 to 7.3 feet in diameter). The round stones lie scattered on the beach, either alone or in groupings.
As on Bowling Ball Beach, the Moeraki boulders are concretions too. The boulders were formed long ago on the ocean floor, and it wasn’t a quick process either. It’s thought that the bigger boulders took up to 5.5 million years to reach their present size! Coastal erosion then deposited the rocks where they’re found today.
The Maori have a more colorful explanation for these boulders. They say that the large rocks are actually the fossilized remains of eel baskets, calabashes (bottle gourds) and kumara (sweet potatoes) that washed ashore from the wreck of a mythical sailing canoe called ‘Arai-te-uru’. It’s said that the body of the canoe’s captain was transformed into the highest rock of a peninsula that lies nearby. Today, the site attracts visitors from around the world.
Image: Nicolas Mirguet
3. Hampi, Karnataka, India
It’s not possible to talk about boulder-strewn landscapes without mentioning Hampi in southern India. Here, the natural monoliths dominate the area. They’re everywhere: clustered together in groups, filling depressions in the land, and perched on top of hills – hills made of more boulders, that is! In fact, boulders aren’t just scattered around the landscape of Hampi; they are the landscape!
Image: Vinoth Chandar
Over the years, people have wondered how all these large rocks came to exist. For some, in the early days, the answer could only be the gods. These people believed that the rocks were the debris of a war between two magical monkey brothers and their armies, who fought to gain control of the Monkey Kingdom. And over hundreds of years, people used these rocks for carving temples, shrines, and even a whole stone city!
Image: © Sami Kuosmanen
We now know that Hampi’s is one of the most ancient terrains in the world. The granite rocks were formed underground about 3 to 3.5 billion years ago. Then the rocks were gradually exposed to the surface by millions and millions of years of gradual uplift and natural erosion. And finally, the rounded boulders were sculpted by wind and sand, which polished and smoothened the stones into the incredible shapes seen today. Make sure you pay this awe-inspiring place a visit one day!
2. Käsmu, Lahemaa, Estonia
Fire, in the form of molten rock, has played a big part in the creation of many boulder fields. But on Käsmu beach, which is part of the Lahemaa coast of Estonia, we see the work of ice. Käsmu has more boulders and rocks than any other place in Estonia. Ancient glaciers moving down from Finland and Sweden deposited the rocks here, and when the ice shelf retreated 10,000 years ago, the boulders remained.
These stones aren’t just picturesque; they also provide scientists with important information about the last ice age. Their placement in moraines, meltwater channels, and other glacial formations indicates the direction in which the ice was moving. And the composition of the rocks also gives researchers vital information about where they came from.
Some of Käsmu’s erratic boulders (which is what these glacial deposits are called) are incredibly large. The largest boulder, ‘The Hermit’, is over 15 feet high and 48 feet in circumference! It’s quite awe-inspiring to imagine stones this big being transported for miles and miles by the power of frozen water.
1. Boulders Beach, Simon’s Town, South Africa
Boulders Beach, near Cape Town in South Africa, may be named after the huge rocks that litter its shores, but most tourists who visit have another attraction in mind: penguins! Boulders Beach is home to a colony of African Penguins that settled there in 1982 and which can be seen frolicking in the water and basking in the sun on the giant rocks.
Image: Adour Garonne
The boulders themselves are made of 540 million-year-old granite! And over millions of years, these stones have been weathered into their current shapes. The surfaces of these rocks are rough rather than smooth, and hard crystals of potassium feldspar are clearly visible.
Image: Johnny Peacock
Nowadays, the boulders of Boulders Beach are beneficial to both the penguins and the humans who swim there. The large rocks shelter the bay from strong currents, big waves, and the wind. And as you can see, they’re also extremely picturesque.
Image: David Burstein
Whether you’re a geologist, a photographer, or just a tourist who likes interesting landscapes, all of the boulder-strewn locations on this list are well worth a visit. Still, perhaps there’s no rush. One good thing about boulders is that they tend to stick around for a very long time.