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Best practice for private metal detecting

A Guide from the Museum of Cultural History, University of Oslo.

When a detector is used to search for metal objects, it is important to remember that you might also find objects, coins or memorials from the medieval and prehistoric period, whether you are actively searching for them or not. Such objects are important, non-renewable resources to our understanding of the past and are protected by the Cultural Heritage Act.

Every year, metal detectorists find important archaeological artefacts in cultivated soils, hereby preventing these artefacts from being further destroyed. But unfortunately, each year, artefacts and archaeological sites are also damaged or destroyed by the reckless use of detectors, either by a metal detectorist who is unaware of what has been found or by the improper treatment of the finds themselves.

The context of the object is often just as important as the object itself. Hence, inadequate information of the find location leads to an irreplaceable loss of knowledge, thus diminishing the objects’ scientific and historic value. Because of this, it is very important that the laws, guidelines and provisions are followed, as well as these recommendations:

Make yourself acquainted with the regulations of the Cultural Heritage Act

And contribute in passing on this knowledge to other detectorists and landowners:
The detectorists need to be aware of the following:

  • It is strictly forbidden to search for artefacts at known archaeological heritage sites (§ 3 and 4). Find such sites.

    Be aware that the locations of heritage sites are not always precisely recorded in the database. For this reason, we recommend that you keep your distance from known archaeological sites. The Directorate for Cultural Heritage recommends a distance of 25 meters. Also, be aware that many sites are not registered and that these are also protected by law. Read more about this (not available in English)

  • All objects that pre-date 1537 AD, coins older than 1650 AD and Sami monuments older than 100 years, are automatically the property of the State of Norway (stray/single finds, § 12 and 13) and must be handed in to the county administration of where the object was found. 

Cooperate with the representatives of the county administration

And follow their advice and guidance. Always remember to bring the relevant contact information of the responsible person at the county administration when metal detecting and contact them if you should find something (within normal working hours).  

You need permission from the landowner

To search for metal objects. This also includes property that belongs to the state.

Make yourself well acquainted with artefacts from the prehistoric and medieval period

So you can quickly identify objects which you are required to hand over to the rightful authorities. Otherwise you might end up discarding important objects of cultural and historic value. For more information on this:

Through the Internet and in social media, there are many groups where you can seek help in identifying objects. The county administrations are able to provide help and the metal detector associations also have knowledge that you may benefit from.

The Museum of Cultural History strongly advices that you LIMIT your metal detecting to areas of cultivated soil

that is, land which is regularly ploughed. Be cautious and stop searching if you have reason to believe that you have discovered an intact archaeological context, which is protected by law.

The Museum of Cultural History strongly discourages metal detecting in all other areas than cultivated soils

such as mountain regions, woodlands etc. These areas can potentially have important archaeological finds that have not been moved or disturbed since they were deposited. Metal detecting in such areas carry a great risk in disturbance, if you should try to recover a metal object. If you retrieve an artefact from e.g. a burial context, you have already destroyed important information about its context. Objects in undisturbed contexts are best left untouched where they were deposited – they are not threatened by destruction in the same way as in cultivated soils. An exception here would be beach areas and similar where the upper 20-30 cm of soil has been disturbed during the last 100 years. Metal detecting in such areas can be conducted, as long as you have received permission from the landowner. 

When detecting in cultivated soils, it is very important that you do not try to retrieve finds from below the plough layer

If it is hard to determine the thickness or depth of this layer, you can ask the landowner. If you are in doubt, you should not dig deeper than 20 cm. You could potentially run the risk of digging into graves, hearths or likewise that have not been damaged by the plough. This can typically occur when larger metal objects are discovered, especially of iron, beneath the top-soil. This is why you should be extra cautious when the detector signals such objects.

All objects must be excavated with great care

Metal objects can have a very fragile and corroded surface, which is easily damaged by careless cleaning. This can result in the loss of thin layers of gilding or fragile, organic remains of textile, wood or leather on brooches and metal fittings. We strongly advise that you do not attempt to clean or in any way scrub the artefact if you suspect it needs to be handed in to the county administrative authority.

Until the object has been properly identified or classified, it should be handled as if the find is to be handed in to the local administration

Always bring zip-lock bags and other packaging material which ensures that finds are not exposed to jolts, pressure or friction. Use one bag for each single object. Label the bag properly so you have no doubts as to where it was found – you should write down the GPS coordinates on the bag. As soon as possible, if the object needs to be handed over to the local administration, send photos of the artefact and information about the find location to the county administration. The Directorate for Cultural Heritage recommends that you report finds on the next business day at the latest.

Bags and boxes with metal objects should be kept in a dark, dry and cool environment, preferably a refrigerator

Do not remove it from the bag or refrigerator – this causes condensation. The object needs to be handed in as soon as possible. If you notice recent corrosion on the object, e.g. a green coating on a copper-alloy object, it must be handed in immediately.

Always bring GPS equipment for recording the coordinates of the find

With the least possible margin of error. We do not recommend a GPS which is intended for use in a vehicle. The GPS should be set to the coordinate-system of WGS 84, UTM 32N. Use the Directorate’s finds form, fill out one form for each object, and enclose it with the object when handing it over to the county administration.

If you suspect that you have come across a burial, a hoard or a collection of artefacts

Which can indicate that the soil contains material from a settlement site or similar, you should stop any further intervention, record the site’s coordinates, and contact the county administration immediately.

Be aware that objects which are not easily identifiable or datable can still be of utmost importance

These can be unrecognizable lumps or pieces of iron, lead or copper alloy (e.g. slag and smelts), which potentially can be important sources to metal-working activity. Should you choose not to record such finds, do not remove them and place these back where they were found. Should you, in close vicinity of slag or metalworking waste, find objects which need to be handed in to the county administration, we ask you to include information about this on the finds form. This provision does not apply to finds which are clearly modern.

Help keep your hobby clean by following

The museum’s best practice for private metal detecting and the Directorate’s guidelines, by promoting these documents to other metal detectorists and alerting the county administration or the police of illegal metal detecting.

The correct use of a metal detector can save objects from destruction in cultivated soils. However, by using a metal detector, you also have a responsibility to ensure that your activity does not damage archaeological monuments or sites. In collaboration with the various county administrations, the Museum of Cultural History will work to promote this guide to best practice for private metal detecting to metal detectorists and their organizations. If there is sufficient cause to suspect that the Cultural Heritage Act has been violated, the museum will, in collaboration with the county administration, actively gather all documentation and report it to the Police.

Published May 15, 2018 10:47 AM - Last modified June 2, 2022 2:43 AM