from the GNU version of the Collaborative International Dictionary of English
- adj. Pertaining to the upper portion of the Laurentian rocks.
from The Century Dictionary and Cyclopedia
- n. In geology, noting a subdivision of the Archæan next above the Laurentian, a group characterized by great masses of gabbro and related anorthosite: proposed by T. Sterry Hunt, who adopted the following succession: Laurentian, Norian, Arvonian, Huronian, Montalban, and Taconian.
Sorry, no etymologies found.