Term: tertiary strata (mining)
Definition:
A series of sedimentary rocks with characteristics which distinguish them from the two other great series of strata, the secondary and primary, both of which lie beneath them.
View pictures relating to mining at Wisconsin Historical Images.
[Source: "Glossary of Miners' & Mineral Terms" in St. John, John R. A True Description of the Lake Superior Country ... (New York, W. H. Graham, 1846).]
