Experiment: Fast-Formed Fossils

by Heather Brinson Bruce on October 1, 2011; last featured January 6, 2019
Featured in Answers Magazine
Also available in Español

Do fossils require millions of years to form? Hardly! Even secular geologists now recognize that rocks form very quickly. The key is the right chemical conditions, not time. See for yourself with a simple experiment.

Everyone knows that the fossils we find all over the world took millions of years to form—scientists proved that years ago, right?

Actually, even secular geologists recognize that fossils form rapidly. If they didn’t, the organism would decay so quickly there would be almost nothing left to fossilize!

Scientists constantly test ways to understand and replicate the process of forming fossils. Taphonomists (those who study how to make fossils) have demonstrated the astonishing speed of fossilization. Some fossils can be generated in days, or even hours!1

Fossils can form in a wide variety of ways. Some common methods include:

  1. The body can leave an impression or mold showing its outer shape in the surrounding sand or mud. This can include footprints and the inside and outside of shells. With the right ingredients and conditions, the mold can harden quickly, like cement.
  2. Petrification takes place when minerals replace the original material of the plant or animal. These petrified fossils must form quickly, before the body parts have time to decay. Petrified wood is a classic example.
  3. Permineralization, or encased fossilization, occurs when dissolved minerals fill the pores and empty spaces in the plant or animal but don’t replace any of the original material. The chemicals then turn into crystals, keeping the organism safe and preserved. While it is possible for many different chemicals to do this, quartz is the most common. Most dinosaur bones are permineralized.

Fossils can form under all kinds of conditions all over the world. While water and dissolved minerals are usually needed to form the three types of fossils above, many processes—coalification, compression, freezing, desiccation (drying out), to name a few—do not require either.

Though there are numerous ways to make fossils, fossilization is somewhat rare today. Why is that?

God created the world to efficiently recycle organic matter. When something dies, scavengers, fungi (like mushrooms), and/or bacteria normally consume it. This process of decomposition leaves nothing behind to fossilize.

However, massive catastrophes like Noah’s Flood would produce the conditions necessary to quickly bury and protect creatures so that they can fossilize. It appears that God wanted to leave abundant evidence of His past judgment of mankind’s sin.

While scientists are still trying to sort out the complex details about fossilization, one fact is undisputed—it can be amazingly fast.

See For Yourself . . .

Fossils are rare today, but you can make them in your own home! Try the following experiment and watch a kitchen sponge “fossilize!”


  • 2 kitchen sponges
  • 1 shallow dish
  • 1 small pot
  • 1 cup of water
  • Epsom salt
  • Food coloring
Fossil Experiment


(Adults should supervise the experiment and perform all cutting.)

  1. Cut both sponges into bone shapes and set one aside. Place the other sponge into a shallow dish.
  2. Heat water close to boiling and stir in as much Epsom salt as will dissolve. Add food coloring to water (if desired).
  3. Pour the salt water over the sponge.
  4. Place the bowl where it will not be disturbed for a few days. Leave uncovered so the water can evaporate.

Final Result

Once dry, compare the two sponges. Break the fossil in half. What happened to the sponge material? Was it encased (permineralized) or replaced (petrified)?

Heather Brinson Bruce earned dual degrees in English and chemistry from Clemson University. She writes and edits for Answers magazine as part of the full-time staff.

Answers Magazine

October – December 2011

Answers magazine has decided to do some myth-busting. This issue will examine some of the most popular myths about the dinosaurs and how they died. Along the way, you’ll learn some other cool facts about these amazing creatures—quick, can you name the smallest kind of dinosaur? We will also examine some serious contemporary issues, such as the increase of biblical compromise in homeschool materials and the dangers of the new leader in “theistic evolution,” known as the BioLogos Foundation.

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  1. Vera Everett, “Soft Tissue Fossilization,” www.answersingenesis.org/articles/aid/v4/n1/soft-tissue-fossilization.


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