Crown research institute geologists finished collecting scores of samples from across Dunedin yesterday to create a "geochemical atlas'' of Dunedin soils.
GNS Science geologists Dr Rose Turnbull and Dr Adam Martin had collected half a tonne of soil samples from 85 sites across Dunedin.
The samples were collected in a grid-like pattern, 1km apart.
The grid-based survey was the first of its kind in New Zealand.
The grid included sites at 38 primary, intermediate and secondary schools across Dunedin.
Nearly 200 Dunedin pupils aged 6 to 18 helped collect the samples.
The two Dunedin geologists were workingd with 25 St
Hilda's Collegiate School
pupils yesterday.
"If we find any gold or silver, we'll be the first to know, so you might see us out in the dark, digging away with head torches on,'' Dr Turnbull joked with the pupils yesterday.
For many pupils, it was the first time they had considered what was "below the surface'', such as volcanic rock, Dr Turnbull said.
The soil samples would be sent to a laboratory in Canada to be analysed for 65 elements.
All schools visited during the project will receive resource material revealing the composition of the soil at their school, how it compares with other parts of the city, and what the differences mean.
The atlas would be a useful baseline for measuring environmental changes and human impact on the soil, Dr Turnbull said.
