Updated: May 27, 2021
If you’ve never been on a fossil or archaeology dig, you may wonder if it’s like what you see in the movies and on television. The short answer is yes…and no. The work is partially done with brushes, but things move a lot more slowly than in the movies. And there is a more to it than just brushing away those final grains of dirt and sand.
The two sciences also approach excavation slightly differently. Archaeology focuses on preserving and studying features and artifacts within their context. Paleontology is a little more destructive of the area in order to get to the fossils themselves.
Let’s break the differences between techniques down:
To ensure the integrity of the finds, features and artifacts, both sciences take specific steps in a specific order.
Archaeologists begin by gridding the site. That is, strings are tied to posts to superimpose a rectangular grid over the whole site. Each grid or “unit” is assigned a number and a team of people. According to the Society for American Archaeology, “This allows the archaeologist to create a precise map to record the exact location of all the features and artifacts on the site.” Gridding always happens before removing any soil or artifacts.
Paleontology can use gridding too, but it’s not a requirement. Paleontologists want to uncover the fossilized bones which can be jumbled together one on top of another. Care is taken with the fossils, of course, but the dirt isn't removed one layer at a time like in archaeology.
In archaeology, scientists use stratigraphy, which determines the relative age of each soil layer and its artifacts and features. The layers on top are newer than the layers on the bottom, according to the Principle of Superposition. Because civilizations have a tendency to build on top of each other, most archaeological sites practice “digging in phase.” This is the meticulous process of even soil removal to retain context and to preserve the stratigraphic relationship to ensure correct dating.
Paleontologists also use the Principle of Superposition to date fossils using the geologic time scale. For the most part, the further down you go, the older the rocks are. Paleontologists, however, must take geologic and seismic activity into account (think Pikes Peak region in Colorado). For confirmation, rocks are dated using radiometric dating. Paleontologists don’t “dig in phase,” but go right to where the fossils are to uncover them.
Tools used in excavation
Archaeologists and paleontologists use many of the same tools in their fieldwork. To remove surface rock, dirt and sand to get to the appropriate stratigraphic level, a lot of digging is required. From small backhoes and shovels to jackhammers and pickaxes, it’s backbreaking but necessary work.
Once the correct level is reached, the finer work can begin. Here, scientists use trowels, brushes, dustpans, sieves and other small tools like awls toothbrushes and knives. Special glues are used to keep delicate artifacts and fossils from breaking apart.
Archaeologists collect artifacts such as tools, clothing and decorations in a few ways. Once something is found, great care is taken with brushes and other tools to to see the object more clearly. It is then carefully removed from the ground. Many smaller items like pottery shards and flint flakes are found by processing soil samples from the site. This is done by sifting dirt through a sieve or adding dirt to water to see what literally “floats” to the surface. Once an artifact is recovered, it is bagged and labeled.
In paleontology, surface fossils and fossilized plants, insects and small fish bones can also be collected from the surface and from microsites. These smaller items are bagged and labeled. For larger fossils, a more time-intensive method is used. Vertebrate and invertebrate fossils are usually chiseled or extracted carefully, while still keeping the rock in place to provide protection. Then, the rock-encased fossils are “jacketed” in burlap and plaster and labeled.
Recording and documenting
Scientists then ensure that all finds are meticulously measured and documented by location. GPS coordinates are used to position finds exactly. Photographs are taken and maps are drawn to document spatial data. Finally, each find is assigned with a number.
And off to the research lab they go!