A DAY IN THE FIELD

From the outside, a fossil dig can look like a treasure hunt. In practice, it is closer to an outdoor laboratory, where every move is planned, recorded and cross-checked so that each fossil becomes scientifically meaningful rather than just an interesting object.

Before the first shovel hits the ground

Serious work in the field starts long before anyone goes near the site.

Choosing a site
Researchers begin by studying geological maps, satellite images, air photos and previous reports to identify rock formations of the right age and type for the fossils they are interested in. They look for sedimentary rocks that were deposited in environments likely to preserve remains, such as river floodplains, lakes, shallow seas or deltas. Access, land ownership and legal permissions are also considered at this stage.

Permits and logistics
Excavation usually requires permits from local or national authorities, landowners or park services, where applicable. The team prepares risk assessments, secures insurance where needed and organises transport, accommodation, food, water and field safety equipment. They also plan how to move large or fragile specimens, which can influence vehicle choice and camp layout.

Research design and priorities
Before arriving, the team defines clear objectives: for example, to map a new fossil-bearing layer, collect specific groups (such as vertebrates, plants or microfossils) or sample a stratigraphic section for diversity studies. These goals help determine which tools, specialists and recording methods are needed.

Arriving at the site: orientation and mapping

Once on location, the first priority is to understand the geology and set up a framework for precise documentation.

Establishing a base map
The team walks the site to identify exposures, measure rock layers and sketch the overall layout. They often use GPS or surveying instruments to create a base map showing key outcrops, landmarks, paths and potential excavation areas. This map will later be used to place all finds in a broader context.

Stratigraphic logging
Geologists measure and describe the vertical sequence of rock layers (a stratigraphic log), noting thickness, rock type, sedimentary structures, fossil content and any signs of environmental change. This log forms the backbone for linking individual fossils to particular horizons and for reconstructing ancient environments.

Setting up grids and reference points
For detailed excavations, the team sets up a grid over the dig area using tapes, stakes and flagging. Each square (for example, 1 × 1 metre) is given a unique ID. A fixed reference point (datum) is established, often with precise coordinates and elevation, so that all measurements can be tied to a common origin.

Locating fossils and deciding what to excavate

Not every fossil seen in the field will be excavated in depth; decisions must balance scientific value, preservation and time.

Prospecting
Team members systematically walk the exposures and surrounding slopes, scanning the ground for weathered-out fossils or fresh breaks in the rock. They note any concentrations of bone, shell, plant impressions or trace fossils such as footprints and burrows.

Assessing significance
When fossils are found, the team considers several factors: rarity, completeness, probable taxonomic identity, association with other remains and the condition of the surrounding rock. A single isolated bone fragment may be recorded and left, while an articulated skeleton or densely fossiliferous layer might justify a full excavation.

Marking and initial recording
Visible fossils are carefully flagged or circled in chalk, and their positions are marked on the site map. Basic information (location, type of fossil, rock layer, finder’s name, date) is entered into a field notebook or digital form even before excavation begins.

Systematic excavation: tools and techniques

Modern excavation is gradual and controlled, with the aim of preserving both fossils and contextual information.

Removing overburden
The first stage is to remove loose surface material and overlying rock (overburden) to reach the fossil-bearing horizon. Larger tools such as shovels, pickaxes and rock hammers may be used at this stage, but always stopping short of the fossil layer.

Working close to the fossils
As fossils come within a few centimetres of the surface, the team switches to finer tools: trowels, awls, dental picks, brushes and occasionally needles. Rock is removed in thin layers, and every new fragment of fossil that appears is noted. The goal is to expose as much as necessary to understand the specimen’s extent and orientation, without risking damage.

Excavation in controlled layers
Whenever possible, excavation proceeds in defined micro-layers, often following natural bedding planes. Material removed from each layer may be kept separate, especially if it contains small bones, teeth or microfossils. In some projects, sediment is screened through sieves to recover tiny elements that would be missed by eye, particularly in microvertebrate or small-mammal sites.

Stabilisation in the field
Fragile fossils are consolidated with reversible adhesives or consolidants, applied sparingly to hold loose fragments together. In many projects, acrylic resins such as Paraloid B-72 are used because they are stable and reversible. If cracks are present, they may be filled to prevent breakage during extraction. This stabilisation is documented so preparators in the lab know what has been applied.

Recording context: notes, measurements and photographs

A fossil without context has limited scientific value. Recording that context is a major part of each field day.

Field notebooks and forms
Each find is assigned a unique field number. The team records descriptive information including fossil type, size, orientation, associated fossils, colour and condition, along with notes on the surrounding sediment, such as grain size, layering, presence of plant material or trace fossils.

Spatial coordinates
Using tapes, compasses, levels or surveying instruments, the position of each specimen is measured in three dimensions relative to the site grid and datum. This allows later reconstruction of the fossil’s original position, even after it has been removed.

Photography and drawing
Photographs are taken at multiple stages: before excavation, during exposure and after full uncovering, often with scales and north arrows included. Sketches in notebooks complement photographs, highlighting features that might be hard to see in images, such as subtle contacts between rock layers or orientations of multiple bones.

Stratigraphic position
The fossil’s level within the stratigraphic log is recorded, often to centimetre accuracy. This includes noting the distance from key marker beds or boundaries and any changes in sediment or fossil content at that horizon. This information is critical for later dating and environmental interpretation.

Packaging and transport: getting fossils safely to the lab

Once documentation and partial exposure are complete, the fossil must be removed and protected for the journey to the laboratory.

Defining the block
Instead of extracting bones individually, the team often isolates a block of rock containing the fossil and some surrounding matrix. Trenches are cut around the block to undercut it, leaving a pedestal of rock that can be carefully reduced until the block can be lifted.

Jacketing
The exposed surface of the block is covered with protective layers such as damp paper or foil. Then strips of burlap soaked in plaster are wrapped around the block to create a hard shell (a jacket). Once set, this jacket holds the fossil and surrounding rock together. For very large specimens, wooden splints, metal frames or foam supports may be added. Monolithic jackets for big skeletons follow the same basic principle at a larger scale.

Labelling and documentation
Each jacket is labelled clearly with its field number, orientation markers (such as arrows showing “up” and “north”) and basic contextual information. The corresponding field notes and photographs are cross-referenced to avoid any ambiguity once the jacket is opened in the lab.

Transport
Jackets are moved using manpower, stretchers, winches or vehicles, depending on their size and the terrain. In some projects, heavy machinery or even helicopters may be used for very large blocks. Care is taken to minimise vibration, impact and extreme temperature changes. For smaller fossils, padded containers or sample bags with internal cushioning are used.

Daily wrap-up: data consolidation and quality control

At the end of a field day, the focus shifts from excavation to organising information.

Reviewing notes and data
Team members review their notebooks, forms and digital records to check for gaps, inconsistencies or illegible entries. Any missing details that can still be remembered or observed on site are added while the information is fresh.

Backing up digital records
Photographs, GPS data and digital forms are downloaded, backed up (often in more than one location) and linked to field numbers. This redundancy helps guard against data loss through equipment failure, weather or accidents.

Updating maps and logs
The site map, grid sketch and stratigraphic log are updated to reflect new excavations, finds and any reinterpretations of the geology. New information may suggest promising areas for the next day’s work or lead to adjustments in the excavation plan.

Planning the next steps
Based on the day’s results, the team decides whether to expand existing trenches, open new grid squares, shift focus to a different horizon or start closing down parts of the site. Scientific priorities, time constraints and weather forecasts all feed into these decisions.

From field to science

By the time a fossil reaches the laboratory, it is accompanied by maps, coordinates, photographs, stratigraphic positions and descriptions of sediment and associated fossils. In the lab, preparators remove the surrounding rock and reveal detail, but the scientific interpretation depends heavily on the field data.

Specific tools, adhesives, grid sizes and recording systems vary between institutions, localities and regulatory frameworks, but the core principles are widely shared: context, careful documentation and reversibility wherever possible. Because of this, a “day in the field” is less about dramatic discoveries and more about patient, systematic work. Good planning, careful logging and thorough documentation ensure that each specimen can be placed back into its geological and ecological context, turning it from an isolated object into a reliable piece of evidence about life and environments in deep time.