Spring is a subtle thing in California.
It's April: drive on the highways in the southern valleys and there is the scent of orange blossoms. This is the beginning of Spring. Not calendars, not daylight savings — no matter where that gets shuffled — but orange flowers in your car windows. During a trip to Death Valley, of course. The hottest place in the world. A dried-up sea.
There are many places to find fossils. Thankfully California is one of them. England and Australia are also good places. Natually, fossils are our best source of information about the prehistoric world. Ever since we uncovered our first dinosaur in the nineteenth century, people have been whiling away their Springs on hands and knees chipping away at beds of sedimentary rock. It was a very fashionable pastime, digging up dinosaurs.
As I write this, satellites passing over the Gobi Desert are relaying images of the red sandstone to Mike Novacek at the American Natural History Museum. The Gobi is one of the most productive fossil pits we've ever found: images from the sky reveal bones exposed from the slow erosion of earth. Before that, crews went in every summer and got lost on unmarked roads and fell from heatstroke. People are serious about their fossils.
Chances are, you won't be employing satellite technology when you take your kid fossil-hunting. Most amateur fossil-finds are a happy product of accident and luck. But it's still worth the bad luck of infinite failed digs to hold a nautiloid shell older than the mountains.
If you've got more than four years of formal education under your belt, you've probably learned how fossils are created. They are a cast of rock made from flesh: meat and shell is replaced with calcite, silica, or iron. The term for it is permineralization. You probably have learned all I'm about to tell you — and more — from cursory trips decades ago to the quarry wearing reflective jackets and hard hats. Consider this an exercise in nostalgia, then.
Where to look
First, get acquainted with your trespassing and environmental laws. You cannot look cool getting cuffed in walking boots and tool belt.
Done? Good. The best places to look for fossils are places that erode quickly: coastlines, riverbanks and cliffs are good naturally-eroding landmarks. Ocean and weather can push a soft coastline back a meter a year. Man-made quarries and other temporary exposures can be an even better place, provided you get permission and safety instructions from the quarry boss before trudging in. To a quarry boss, you are a wrongful death lawsuit waiting to happen.
You'll want a geological map to locate areas with sedimentary rock. This is where most fossils are found: in layers of limestone and sandstone piled on with the slow movement of geology. Of course, not all sedimentary rock contains fossils. Your local natural history museum or rock club should be willing to provide you with established, already-found dig sites.
People use satellites now to find fossil beds. That's a bit sterile for our tastes.
As an amateur fossil hunter, you will need:
- A waterproof jacket
- A high-visibility (read: reflective) jacket
- Walking boots
- A hammer
- A hard hat
- Containers for finds (newspaper wrapping should work nicely)
- A chisel
- A magnifying glass
- Food and water
- A tide chart, if you're searching the beach
- A cellphone
- A map or local guide
Of course, if you're digging in clay you probably won't need chisels and hammers. This is why searching the coast is so nice: you're digging through soup. Inland, the earth has had millions of years to solidify.
You'll notice that a good portion of your tools list is made up of safety gear. Cliff faces have falling rocks, deserts have sun, quarries have machines.
Down to business
If you're searching a brookbank, move upstream until you find large, angular pieces of bone. Streams flowing from sites claimed by paleontologists are good streams to search.
Coastlines have on-seasons and off-seasons. Rough seas remove layers of extraneous sand, exposing clay. This is good. Some seasons deposit so much sand that all but the highest outcroppings are covered: this is bad.
You'll want to find a quarry that is working.
If you must split rock, do it delicately. Use a geology hammer — a hammer with a pointed tip — or, better yet, a hammer and chisel for more controlled strikes.
Stop occasionally to marvel at the carbon cycle and at the chemistry of flesh and rock. Atoms never break. Some of us will fossilize someday and come up in riverbed sediments and folds of limestone.
I could write you an entire book on fossil identification. I have purchased entire books on fossil identification. Fossils are remnants of ancient life: life is a dynamic phenomenon.
If you've found something that looks like a tire track, you've got lycopod tree bark.
If you've found something that looks like a brain, you've got a stromatoporoid.
If you've found something that looks like a trilobite, you've got a trilobite.
For each example above, there is a valid counterexample. Fossil identification is a deep and wide ocean.
Look here for an excellent — and free — identification resource.
If you'd like to be more adventurous, contact the paleontology department at your local museum. Or brave the halls of the local university library. The slowest, most inefficent, and most enriching route to identification is to study up on similar living creatures, wherever they may exist.
So you'd like to sell or trade fossils.
First, identify them as thoroughly as you can. Document their location and species. Don't trade based on aesthetics, even though these things are beautiful. Your fossil loses monetary and scientific value if you hand it off without accompanying info. Fossils are not baseball cards.
Second, protect fossils while transporting them.
Third, beware of fakes. People have ways of duplicating real fossils. Use your common sense.
Tegowski, BJ. Easy Field Guide to Invertebrate Fossils of California. Premier: Phoenix. 1995.
The Natural Canvas
Colossal Fossil Site
University of Kentucky