Cave bacon in Soldier’s Cave, Sequoia and Kings Canyon National Parks, Calif.
Cave bacon in Soldier’s Cave, Sequoia and Kings Canyon National Parks, Calif. Credit: Kristen Ankiewicz, CC BY-NC-SA 2.0

Holidays are about celebrating with people you love, especially over food. Whether you’re sneaking an early taste of your mom’s secret gravy recipe or licking pumpkin pie off your fork, food holds a special place in traditions, in fun, in memories old and new.

But this holiday season, while you’re stuffing your mouth with turkey and slathering butter on a freshly baked roll, chew on this: Geoscientists have their own unique relationship with food. They see it in the features that they study.

Here are eight food-themed formations from geology and space science that might just make your mouth water.

Care for a Snack of Cave Popcorn?

Cave popcorn in Ali Sadr Cave, Iran.
Cave popcorn in Ali Sadr Cave, Iran. Credit: جواد, CC BY-SA 3.0

Cave popcorn, also known as cave grapes, are small, lumpy calcite formations that can be found sprinkled throughout limestone caves. Like many cave features, cave popcorn forms because calcite that starts out dissolved in water and carbonic acid rains out of the solution.

The trick to making cave popcorn—as opposed to a stalagmite or stalactite—is having just the right conditions. The tiny bumps can arise when water seeps out of a wall or splashes as it drips.

Cave popcorn can be pale white like popcorn waiting for all the fixings or a deep yellow, reminiscent of the butter-soaked mounds behind the glass at a movie theater concession stand. Refills, please!

Pass the Breadcrust Bomb

A breadcrust comb from Craters of the Moon National Monument and Preserve, Idaho.
A breadcrust comb from Craters of the Moon National Monument and Preserve, Idaho. Credit: NPS, CC BY 2.0

That crunch you hear from pressing the crust of freshly baked bread? Yeah, it’s almost like that.

To geoscientists, a bomb is a rock that is over 64 millimeters (about 2 inches) in diameter that forms when molten lava is hurled from a volcano. If the outside has hardened but the inside is still soft, gases trapped in the rock can expand and crack the outer skin like a rising bread loaf. The impact of the bomb hitting the ground can also crack the hard shell.

These cracks can leave a pattern that sometimes looks like the cracked crust of bread, earning these rocks their name. A fun note: Volcanic bombs that get flattened during their landing are sometimes called pancake bombs.

A 3-meter-long slice of cave bacon in Jewel Cave National Monument, Wyo.
A 3-meter-long slice of cave bacon in Jewel Cave National Monument, Wyo. Credit: NPS

That Irresistible Smell of…Cave Bacon

In a world with bacon mints, bacon vodka, and bacon soap, geoscientists give you nature’s own streaky rasher: cave bacon.

Also called flowstone, cave bacon forms when water smoothly runs down an overhanging wall over and over. The mineral buildups produce a long, thin sheet, with undulations similar to crisp slices of bacon. Variations in the chemicals in the slowly dripping cave water even create colored stripes akin to alternating bands of fat and meat.

Now, if only it popped and sizzled in the mornings….

You Can’t Have Your Yellowcake and Eat It Too

Yellowcake uranium
Yellowcake uranium. Credit: Nuclear Regulatory Commission/Energy Fuels Inc., CC BY 2.0

Care for some moist, springy yellow cake with a thick coating of chocolate for dessert? Just make sure the baker didn’t get any actual yellowcake in the mixing bowl.

Yellowcake, without that very crucial space between the words, is the powder form of uranium oxide. It is made when preparing fuel for nuclear reactors from mined uranium.

Like any good cake, there are a couple of ways to cook it up. You can mechanically grind the uranium ore and dissolve the uranium oxides with acid. Or you can skip the mining and dissolve the uranium into groundwater with a high oxygen content, which can then be pumped to the surface.

The produced powder is often yellow, resembling the dry mix found in your grocery store’s baking aisle. However, the color of yellowcake depends on the drying temperature and can even be dark green.

Sink Your Teeth into Taffy Terrain

Taffy terrain in Hellas Planitia, Mars. The image shows an area of about 3 kilometers from top to bottom.
Taffy terrain in Hellas Planitia, Mars. The image shows an area of about 3 kilometers from top to bottom. Credit: NASA/JPL/Malin Space Science Systems

No, that isn’t the sweet, chewy boardwalk treat that has been pulled every which way. It is hard Martian rock. But it looks yummy, right? That may be why planetary scientists informally refer to such formations as taffy terrain or taffy-pull terrain.

The origin of the formation’s swirls and bands—found only in a flat plane on Mars called Hellas Planitia—is uncertain. Rather than being pulled into the pattern, these gooey-looking streaks could be the product of gentle erosion or the scars of debris flows.

And Now for a Cheese Course…on Mars

Swiss cheese ice formations near Mars’s south pole.
Swiss cheese ice formations near Mars’s south pole. From left to right, the image spans about 3.5 kilometers. Credit: NASA/JPL-Caltech/University of Arizona

In case you don’t have a sweet tooth, taffy is not the only food that planetary scientists are seeing in Martian terrain. There are also pockmarks in ice caps near the Martian south pole, which planetary science informally terms Swiss cheese. Large, irregular holes in the ice pole make it look ready to be sliced and served with crackers.

On Mars, ice caps are not made of just frozen water but have a coating of frozen carbon dioxide, commonly called dry ice. A fun feature of dry ice is that it sublimates, meaning it skips being a liquid as it goes from being a solid to a gas. This process is believed to leave behind the depressions that create the distinctive cheese-like appearance.

A Palate Cleanser of Martian Blueberries

Blueberries on Mars’s Meridiani Planum
Blueberries on Mars’s Meridiani Planum. Credit: NASA/JPL-Caltech/Cornell University

Clear your palate with the sharp tang of…Martian blueberries. The gray-blue-tinged mineral spheres are strewn across a flat Martian plane named Meridiani Planum and look like blueberries garnishing a rock cake. Some are lightly embedded in the rock itself, like a blueberry-studded muffin. Although the spheres are only at most about 6 millimeters in diameter, the nickname is an apt fit.

Mars’s blueberries are believed to be hematite-rich concretions that formed after water heavy with dissolved iron diffused through the surrounding rock. However, some scientists think these berries may be food from the sky—small pieces of meteorite.

When NASA’s Mars Exploration Rover Opportunity studied these blueberries in 2004, it helped establish the idea that Mars used to have watery environments. The spheres’ composition was identified using a collection of blueberries in a depression in a rock known as the “Berry Bowl.”

Help yourself to the fruit!

Don’t Cry Over the Spilled Milky Way

The Milky Way
The Milky Way. Credit: Dave Young, CC BY 2.0

It’s not a feast until someone makes a mess, right? Our home galaxy of the Milky Way has been said to look like spilled milk, but it is far more likely to take your breath away.

As we gaze out at the rest of our galaxy, the billions of stars blur together to form a milky trail that crosses the night sky. On a dark, clear night, the view of the rest of the Milky Way from our small planet puts into perspective how miniscule a glass of spilled milk really is.

The Milky Way has long summoned images of milk to peoples’ minds. The first known use of the name Milky Way is from the 14th century, but even earlier, this feature of the night sky was referred to in Latin as “Via Lactae,” meaning the milky road or way. The very word “galaxy” has its origins in the Greek word “gala,” meaning milk.

Enjoy the feast!

From cave popcorn to fruitlike nodules, Earth and planetary formations provide much food for thought to make your mouth water.

Do you have a favorite science word that sounds delicious? Tweet it to @AGU_Eos and tag it with #ScienceFeast.

—Bailey Bedford (email:; @BBedfordScience), Science Communication Program Graduate Student, University of California, Santa Cruz


Bedford, B. (2018), Cave bacon and other delectable science terms, Eos, 99, Published on 21 November 2018.

Text © 2018. The authors. CC BY-NC-ND 3.0
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