Buzz
This diagram illustrates how the rhino formation was probably revealed by a glacial flood, positioned 200 feet (60 meters) above Blue Lake in Washington. It highlights the bubble-filled basalt from a past lava flow, the pale sandy sediments that once formed the lake's floor, and the surrounding pillow basalt around the cave. Courtesy of the Burke Museum.Key Insights
- A cave in South Africa bears a striking resemblance to a rhinoceros.
- Known as Rhino Cave, this natural feature was discovered within the Cradle of Humankind World Heritage Site.
- Rhino Cave offers significant potential for both archaeological and paleontological studies.
Not all fossils are bones, shells, or teeth. While mammoth tusks and Stegosaurus spikes are undeniably fascinating, the fossil record goes beyond just body parts. Fossils are defined as any "naturally preserved remains or traces of [life forms] that existed in the geologic past."
If I may make a pun, this definition covers a lot of ground. Fossils can appear as footprints, leaf imprints, or even the filled-in tunnels left behind by ancient land beavers.
One of the oddest fossils ever found is actually a cave. Around 15 million years ago in eastern Washington state, a volcanic eruption caused lava to flow into a shallow river or lake where a rhino was wallowing.
A layer of basalt rock solidified around the creature, preserving the shape of its (rather well-cooked) body. For millennia, this rhino-shaped cavity remained concealed within the cliffs of Grant County, Washington, near Blue Lake, a popular hiking spot.
By the 1930s, erosion had created a gap in one end of the underground rhino mold, bringing it into the open. This is the tale of how the "Blue Lake Rhino Cave" was formed — and how four Seattle rock hounds stumbled upon it by chance.
The massive Grand Coulee and the expansive Channeled Scabland, which cut through much of the Columbia Plateau, were likely formed in just a few weeks during the last Ice Age when a nearby ice dam suddenly collapsed, unleashing a torrent of water. Courtesy of the Burke MuseumAmerican Rhinos
Currently, only five species of rhinos exist, and none of them are native to North or South America. However, between 40 to 70 million years ago, rhinos were widespread across North America. Some species, such as the barrel-shaped Teleoceras, were semi-aquatic, resembling hippos. Others had sharp tusks instead of the characteristic nasal horns seen in modern rhinos.
Paleontologists believe that the Blue Lake Rhino Cave likely formed around the remains of a Diceratherium. This species of rhino was sexually dimorphic, meaning males and females had visible differences. Female Diceratherium lacked horns, whereas males sported a pair of small horns positioned side by side near the tip of their snouts.
The dimensions of the Blue Lake cave suggest that the Diceratherium which left its trace was approximately 8 feet (2.4 meters) long from snout to tail, and stood just under 4 feet (1.2 meters) tall at the shoulder. This creature likely weighed around 1 ton (0.9 metric tons) in life.
It's uncertain whether the creature was dead when it became entombed, but the mold's contours indicate the body was likely bloated, a sign that decomposition had begun. The positioning of the legs suggests the rhino might have been floating on its back, possibly in rigor mortis.
The cave's walls are composed of 15-million-year-old pillow basalt, a type of igneous rock formed when lava interacts with cold water and cools rapidly. Whether alive or dead, the Diceratherium must have been submerged in water during a volcanic eruption, after which lava poured in.
Lava can reach temperatures above 1,600 degrees Fahrenheit (900 degrees Celsius). Normally, such extreme heat would have incinerated the creature's skin, flesh, and bones, but the cold water caused the molten rock to solidify into a dense layer of pillow basalt.
The body eventually decayed, and most of its bones were lost. However, the mold that enveloped the creature remained mostly intact.
Mostly, though not entirely.
The rhino cave (shown on the right) was first discovered in the summer of 1935 by two couples who were hiking high on the cliffs in search of petrified wood.
Courtesy of the Burke MuseumA Chance Discovery
When you stop to think about it, it's quite remarkable that we even know this unusual little cave exists. Millions of years after its formation, flowing water carved an opening in the mold, right around where the rhino's hindquarters once were. Yet, erosion hasn't completely destroyed it.
Today, the entrance to the Blue Lake Rhino Cave is large enough for an adult to enter. However, navigating inside could be challenging for some visitors. The cave itself is perched on the side of a cliff, towering about 300 feet (91 meters) above the lake that shares its name.
In the summer of 1935, two adventurous couples from Seattle, the Peabodys and the Frieles, were exploring the cliffs in search of petrified wood. During their hike, they stumbled upon the cave, and Mr. Haakon Friele made history as the first person ever recorded to enter the prehistoric rhino mold.
Inside the cave, Friele discovered a collection of fragmented animal bones, including a partial jaw. These fossils were sent to paleobotanist George F. Beck at Central Washington University, who couldn’t resist visiting the cave to examine them firsthand. He then enlisted the help of Chester Stock, a paleontologist from the California Institute of Technology, to identify the bones.
Stock's analysis revealed that the bones belonged to an extinct rhino species. It was soon realized that the cave itself was essentially a full-body mold of the same animal, a creature that had been extinct for 15 million years.
In 1948, a team from the University of California at Berkeley scaled the steep cliff and filled the cave with plaster, effectively creating a three-dimensional replica of its interior. Additionally, an exact hollow copy of the cave was later displayed at Seattle's Burke Museum.
Trying to venture into the actual cave can be risky due to the steep cliff surrounding it. But don’t worry, you can always enjoy a musical tribute! The Ratfish Wranglers, a science-focused rock band fronted by paleoartist Ray Troll, perform a fun and fossil-filled song titled "Blue Lake Rhino."
One of the largest land mammals ever was Paraceratherium, a distant relative of today's rhinos. This long-necked herbivore measured about 26 feet (8 meters) in length and could have weighed over 22 tons (20 metric tons).
