Eyes remain the most valuable tool that divers can use to survey an area for artifacts. However, it takes special tools to spot buried objects. Divers use a tool called a magnetometer to find hidden artifacts that contain iron.

To think about:
Can you find buried objects made of other materials like glass or wood? What kind of new tool would you invent?

Like a crime scene, the way in which artifacts are scattered on the ground may reveal important clues, so archaeologists are careful to record the location of all objects before removing or even touching these objects.

Even underwater, archaeologists lay out a grid and very carefully survey the site to measure its dimensions and locate all objects within it. Divers use this grid to note the locations, orientation, depth, and relationship to other objects of all artifacts they encounter. Each item, whether a chamber pot or a piece of a building foundation, is carefully sketched and given a unique identifying number before it is disturbed in any way.

Space (or "spatial) relationships are important not only with respect to horizontal distribution, but in the vertical direction. Horizontal relationships might reveal how things were arranged in space at a particular moment in time, but vertical relationships can reveal relationships of objects over time. For example, in Venice, Italy, people kept building upward as the city of Venice sank, so progressively older artifacts are found by digging deeper.

At the Ocean Institute
Students and visitors to the Ocean Institute can try their skills at using a magnetometer to find buried artifacts.

Diver using a magnetometer to scan a shipwreck. Image courtesy Institute of Nautical Archaeology.

Magnetometer at the Ocean Institute. Visitor looking for buried artifacts in the test tank. Image from the Ocean Institute. All that you can do at OI