The largest archaeological digs in Victorian history took place in the heart of the CBD as part of the Metro Tunnel Project. Here's how they were undertaken.

Video overview

Phases of the process

Historical research

Archaeologists and historians will research historical archives of written records to understand how the site was used since European settlement in the mid 1830s up until the present day.

This includes how the site may have been disturbed over time by different uses and building phases.

This leads to an understanding as to whether there is likely to be archaeological remains on the site and if so, what kinds of remains and where they might be located.

As archaeological sites are protected under the Heritage Act 2017, before doing any field investigation a consent is required from Heritage Victoria.

Stage 1 – Field investigation: uncovering

As archaeological investigation usually involves trying to work out what is hidden under the surface of the ground a carefully planned excavation program is required.

This starts with an initial phase of uncovering the site, which means removing all modern structures and fill to get to what are potential old archaeological layers.

Once these early archaeological deposits have been uncovered, the site is ready for the full excavation.

Stage 2 – Field investigation: excavation

Archaeologists create accurate maps and scale drawings of surface features across the site before conducting full site excavation.

Full excavation involves the careful peeling back of the different occupation layers or phases of occupation across the site.

The archaeologists look for changes in the colour and texture of the soil, which helps determine when they could be reaching a new phase in occupation of the site.

All features such as old walls, wooden stumps, fire hearths etc. must be properly exposed (with trowels and brushes) before they are photographed with scales.

Each individual layer of soil and artefact is dug separately. All artefacts must be excavated carefully as they can be very fragile.

It is also very important that the context of the artefacts is carefully recorded and that this is reflected on the labels for each bag with numbers of where they were found on the site plan. Then they can be analysed properly at a later stage.

Artefact analysis is a very important part of the archaeological excavation process as it enables archaeologists to understand the age of the deposits being excavated.

Where suitable most artefacts are washed or brushed to ensure that they are clean for examination and cataloguing.

All fragile artefacts are treated by a conservator who is trained in proper conservation treatment of artefacts. This ensures that they are preserved for future generations.

Stage 3 – Post excavation

Once artefact processing is complete, the Artefact Manager will catalogue each artefact.

This can be a time-consuming procedure, nevertheless it is very important that artefacts are recorded to the standards required by Heritage Victoria.

Once all artefacts are conserved and catalogued they are lodged with Heritage Victoria in appropriate conservation boxes.

All field information is written up in the office to ensure that the site is properly recorded and analysed.

A report is then pulled together outlining the site history, the methodology followed for the excavation, the artefact analysis, and a final analysis of the findings from the field.

After the excavation is completed, a consent is then provided by Heritage Victoria so that the site can be impacted by the development.