Paleontology Contact

Sandy Ebersole

205.247.3613

How to Collect Fossils

 

Safety

Fossils are collected outside, sometimes in wild areas, and safety should be a major concern when you are out in the field. With careful planning, sufficient numbers of chaperones, and restriction of visits to the safest areas, fossil collecting trips can be fun for all. Snakes and poison ivy are the two greatest dangers at Alabama outcrops. If a member of your party is bitten by a snake you think is poisonous, you should get that person to the nearest hospital as quickly as possible. If you can, bring the snake (dead), a digital photo, or at least a description of it so that hospital personnel will know how to treat the injury. Other dangers may include ticks, stinging insects, black widow spiders, toxic plants, holes and loose rocks, broken glass, and barbed wire. You can minimize the risk of encountering snakes, poison ivy, and other pests by taking field trips in the winter. However, on a cold day students will be reluctant to get their hands dirty, and they won't learn as much. It is best if you can be flexible about when you go to the field, so you can choose the most pleasant days.

 

In the summertime, heat exhaustion is a very real danger. Everyone should have a hat and plenty of liquids to drink. A quart per person is a good minimum unless your time in the sun will be very short. Summer field trips should start early and end early to avoid the heat.

 

Many fossil-collecting sites are road cuts. Road cuts are highly accessible, easy to find, and numerous, but they also can be dangerous. Think carefully before taking young children to any road cut. If you do take students to a road cut, you will need more chaperones per child than on other kinds of field trips.

 

Road cuts may have narrow shoulders that keep students close to the road. In such cases, traffic will be a problem. Even where shoulders and ditches are wide, the usual dangers from heat, etc., may be encountered at road cuts.
Some fossil-collecting sites are abandoned quarries. Cliffs, loose rocks, and deep lakes are some of the special hazards of such localities.

 

Data Collection

Recording site data is the first thing you must do after ensuring the safety of field-trip participants. Fossils are the subjects of scientific study, and as such we need to know where they came from. A fossil from an unknown location is little more than a very old paperweight. This is because there is a lot of information to be gained from fossils beyond their names and appearance. The environment of deposition (indicated by characteristics of the enclosing sediment or rock) and age of a rock unit are two of the most important things we can learn from the study of fossils.

 

Your field notebook should include descriptions of all outcrops you visit. At the very least, you should record enough information to find the outcrop again! Your field notebook should also include a list of samples collected and photographs taken, as well as any significant observations you made. When you collect a sample, mark it or its container with an indelible marker. Include your initials, the name or number of the outcrop, the date, and, if known, the rock unit from which the specimen was collected. Cloth bags with drawstrings for larger samples, and 35-mm film canisters for smaller samples are favorites with many fossil collectors. Cigar boxes or other small boxes are also used. However, be creative. In many cases paper or plastic bags will be quite satisfactory. Fragile specimens might need to be wrapped in aluminum foil, tissue paper, newspaper, or other cushioning material.

 

It is a good idea to sketch or take an instant photograph, or a digital photo of the outcrop and mark the spot from which the fossil was collected, if it was found in place (still embedded in its original position on the outcrop). The different rock layers exposed at an outcrop may be very different in age, appearance, composition, environment of deposition, and fossil fauna. For example, the famous Cretaceous-Tertiary boundary layer, which has yielded evidence of the impact of a giant asteroid, is in many places only a few centimeters thick.

 

Different kinds of rock demand different approaches to fossil collection. For instance, the marine fossils of the Alabama Cretaceous near Livingston, Alabama, weather out of their matrix and lie scattered on the sediment surface. Digging for them is not very helpful, because some are fragile and others are sparsely distributed in the sediment. A dry outcrop that has not been visited recently may be literally covered with fossil shells that simply can be picked up. Bear in mind that it may take years for this number of fossils to weather out of the rock. Collected fossils should be placed in closed bags and marked with a code name or number for the outcrop that corresponds to the outcrop description in your field notes. Fresh surfaces of the hard fossiliferous limestones of north Alabama do not show fossils well. Lightly weathered outcrops may show fossils in beautiful relief. Severe weathering tends to ruin fossils on hard limestone surfaces. Fossils in shales commonly look best on fresh surfaces and fade quickly upon weathering.

 

Some rocks contain trace fossils: burrows made by worms, ghost shrimp, and other organisms. Some burrows are mineralized (filled with iron minerals) and can be collected like the shells. If the burrow is collected in place, mark with an arrow indicating which direction is up. Other burrows are revealed only as color contrasts in the sediment, and are best "collected" with a camera. When you take photographs in the field, be sure to keep a list of all photographs taken. This list should include date, location, and subject. Also, because some geological features resemble others of vastly different size, you should always place a scale in the photograph. This could be a small ruler, rock hammer, coin, or person. A ruler marked boldly in inches and centimeters is the best scale for most outcrop photographs.

 

The preparation of fossils for study is a subject that has filled dozens of books. Techniques range from how to take high-contrast photographs of objects that are essentially gray-on-gray shapes to methods of using computer modeling to reconstruct three-dimensional objects that have been sliced very thin.
Many techniques are expensive and difficult, but some of the basic methods are easy to master, inexpensive to apply, and can yield excellent results. Useful tools of the field collector include a hand lens (magnifying glass) and a small brush. The hand lens allows the geologist to examine small objects, like fossils, in much more detail than would be possible with the unaided eye. The brush is used to sweep dust and dirt from fossils. These two simple tools can make fossil collecting fun and educational. Other tools that are useful in the field include (1) a water bottle - many fossils are easier to see (have higher contrast) when wet, (2) a camera with a close-up lens for fossils that cannot be collected because of their size or fragility, (3) a good map, (4) a hat for protection from the sun, and (5) a rock hammer. One more tool is essential, and this is common sense.

 

When it comes time to study fossils, you may find that they are easier to study in oblique light. This is light coming from a low angle (like the sun's light shortly before sunset) and it casts small shadows that reveal the fossil's smallest features. Some fossils may be partially covered by rock matrix. This material may be removed by use of dilute acid (vinegar often works), with a sharp pick or knife, by using an ultrasonic or soapy bath, or by other methods. All such methods involve risk to the fossils, and the best way to proceed is to experiment on unimportant or unattractive specimens that were preserved the same way (and came from the same site) as the specimens of interest.

 

Site Conservation

 

In collecting fossils we must always think of preserving the site for others. Readily accessible outcrops containing attractive fossils are visited often. These visitors may be children, teachers with their classes, commercial fossil dealers, amateur fossil collectors, or paleontologists. Collect sparingly, and do not denude or damage an outcrop so that others cannot use it. Be especially careful not to step on the fossils that lie scattered on an outcrop. Outcrops may take years to return to their pristine state after suffering such damage.

 

If you find anything unusual, such as a vertebrate bone or skull, contact the nearest natural history museum or university geology department, or the Geological Survey of Alabama, to find out if the specimen is valuable for scientific study. Museum and university geologists can tell you which areas are currently being studied and should not be visited by large groups, and which areas can be visited by students without hindering research. In many cases you can cooperate with scientists by locating rare finds that can be studied or displayed in museums. If you find a rare specimen and are willing to lend it to a museum, you will be given full credit in the display or record.

Fossil Locations

The Geological Survey of Alabama does not provide locations for hunting fossils. The GSA recommends contacting a group such as the Alabama Paleontological Society or the Birmingham Paleontological Society if you are interested in a collecting field trip.