PLANET EARTH

How Are Fossils Formed?

How are fossils formed? For fossil formation to take place a series of fortunate events must occur. If any part of the series is missing, we will never see the fossil! In fact, fossilization is a rare occurrence. Nature tends toward recycling. That includes just about everything from plants and animals to rocks and minerals.

Let’s narrow it down to just animals for a minute. Animals, dead or alive, are food for other animals. From insects to dinosaurs, an animal could be someone’s lunch! Any part of the animal’s body that isn’t consumed is usually scattered about; leftovers! Just like those leftovers in your fridge, these leftovers make great food for bacteria. In addition, these leftovers are exposed to the elements: sun, rain, and even the soil itself all help to breakdown and decompose the sturdiest of bones, shells and wood.

If we are ever going to see a fossil, some very specialized events must intervene to ward off the natural process of decomposition. The following is the most common scenario for fossil formation:

How Are Fossils Formed? Death Is The First Step

To start with, an animal or plant must die in water or near enough to fall in shortly after death. The water insulates the remains from many of the elements that contribute to decomposition. An example may be helpful. Let’s say that a trilobite has died of old age on the bottom of the sea. Bacteria consume the soft body parts but leave the hard exoskeleton intact.

How are fossils formed? Step two is Sedimentation

As time passes, sediments bury the exoskeleton. The faster this happens the more likely fossilization will occur. Land and mudslides definitely help. River deltas are also good for quick accumulation of sediments. This further insulates our trilobite from decomposition.

The sediments themselves have a huge influence on how well our Trilobite Fossil turns out. Very fine-grained particles, like clays, allow more detail in the future fossil. Course sediments, like sand, allow less detail to show. The chemical make up of the sediments also contributes to the future fossil. If iron is present, it may give the rock a reddish color. Phosphates may darken the rock to gray or black. The possibilities are truly endless.

Permineralization

As the sediments continue to pile on, the lower layers become compacted by the weight of the layers on top. Over time, this pressure turns the sediments into rock. If mineral-rich water percolates down through the sediments, the fossilization process has an even better chance of preserving our ancient animal. Some of the minerals stick to the particles of sediment, effectively gluing them together into a solid mass. These minerals make an impact on our original trilobite as well. Over the course of millions of years, they dissolve away the outer shell, sometimes replacing the molecules of exoskeleton with molecules of calcite or other minerals. In time, the entire shell is replaced leaving rock in the exact shape of the trilobite.

Uplift

As the continental plates move around the earth, crashing into each other, mountains are formed. Former sea floors are lifted up and become dry land. This is exactly what has happened to our trilobite. Now a fully formed fossil, our trilobite is buried under hundreds or even thousands of feet of rock! Thanks to the movement of the plates, our trilobite will come closer to the surface and nearer to discovery by some fortunate fossil hunter. Luckily, nothing stays the same.

Erosion at work

Rain, wind, earthquakes, freeze and thaw all work toward erosion. The mountains that were built up are worn away over time. Our fossil trilobite once again sees the light of day! With a little wisdom about where to look and some luck, you may be the first one to find him!

This is the fossilization process known as Permineralization. It is not the only answer to the question: “How Are Fossils Formed?” There are many other ways that fossils can be formed. You can read about them using the links below.

About the Author

Claudia Mann is a teacher, and a contributor to http://www.fossils-facts-and-finds.com Claudia and her husband own http://www.fossilicious.com, a place to find great fossils at great prices.

Diatomaceous Earth Food Grade 10 Lb $10.48 This fossilized skeletons of tiny aquatic organisms. When untreated, the razor sharp edges of this mined product scratch the exoskeletons of hard bodied insects, making them susceptible to fatal attack from natural organisms in the soil. Application rate: Dry: 1 lb. per 500 sq. ft. Solution: 2 tbs. per gal. of water. As a food supplement for pets: 1-2% of food volume….

Diatomaceous Earth Food Grade 5 Lb $8.69 This fossilized skeletons of tiny aquatic organisms. When untreated, the razor sharp edges of this mined product scratch the exoskeletons of hard bodied insects, making them susceptible to fatal attack from natural organisms in the soil. Application rate: Dry: 1 lb. per 500 sq. ft. Solution: 2 tbs. per gal. of water. As a food supplement for pets: 1-2% of food volume….

Perma-Guard Diatomaceous Earth DE Food Grade 50 lb bag $24.47 Food Grade Diatomaceous Earth (Fossil Shell Flour) has many uses: in the household, with pets, on plants, around livestock, and for stored grain. It is totally organic and listed with OMRI. With more than 600 deposits of diatomite west of the Mississippi-and only four (to our knowledge) that can be considered food grade-it is very important that people know what they are using. The vast majority …

Wallmonkeys Peel and Stick Wall Decals – Baltic Amber – Removable Graphic WallMonkeys wall graphics are printed on the highest quality re-positionable, self-adhesive fabric paper. Each order is printed in-house and on-demand. WallMonkeys uses premium materials & state-of-the-art production technologies. Our white fabric material is superior to vinyl decals. You can literally see and feel the difference. Our wall graphics apply in minutes and won’t damage your paint or l…

Young Scientist Series – Set 3: Minerals (Kit 7) – Crystal (Kit – Fossils (Kit 9) $16.90 Conduct Earth Science experiments in your very own living room. Grow a salt rock garden, rock candy and string crystals. Break open a large Geode. Identify five unknown minerals using the streak, hardness, magnetic and acid tests. Study a fossil. And finally, complete this set by making a cast and a mold fossil that will impress any budding scientist….

Nature Series: Science on a Nature Walk $17.50 Field experiments galore! What can be more fun than exploring science through real field experiments on a nature walk? Find animal tracks and fossilize them. Find treasures on a scavenger hunt. Make your own compass. Perform leaf chromatography. Make a bug house. This Young Scientists Club Kit includes all the necessary tools such as binoculars, butterfly net, magnifying glass with whistle, chroma…

Insects in Amber (Miocene) Fossil Specimen …

Columbia Men’s Bug Shield Long Sleeve Shirt $79.95 Skip the undignified waving and slapping, not to mention the nasty chemicals like DEET, when you want to keep biting bugs from ruining your day outdoors. The Columbia Men’s Bug Shield Long-Sleeve Shirt offers an effective, natural way to keep the bugs at bay with a built-in, long-lasting plant-based insect repellent.Product FeaturesMaterial: polyester ripstopFit: regularCenter Back Length: Pockets…

Columbia Womens Bug Shield Pant $79.95 Match the Columbia Bug Shield Women’s Pants with the Bug Shield Shirt for a full bug-free outfit that lets you paddle, hike, and play comfortably in mosquito-filled country.Product FeaturesMaterial: Bug Shield Summit Cloth (nylon)Fit: relaxedInseam: 32 inOutseam: Cuff Width: Waist: buttonRise: regularPockets: 2 hand, 1 thighFly: Gusseted Crotch: yesSPF Rating: UPF Rating: 50Weight: Recommended Use…

Columbia Men’s Bug Shield Crew Long Sleeve Tee $59.95 Unless you’re lucky enough to be trekking across mosquito-free high-altitude trails, any hiking trips you take this summer will call for the Columbia Men’s Bug Shield Long-Sleeve Crew Shirt. This performance top not only blocks UV rays and wicks moisture for maximum comfort, but it is treated with Columbia’s Insect Blocker technology for bug-free enjoyment of the great outdoors. This plant-based t…