The Stenian (from Greek stenos, "narrow") is the final geologic period in the Mesoproterozoic Era and lasted from 1200 Ma to 1000 Ma (million years ago). Instead of being based on stratigraphy, these dates are defined chronometrically.
Name derives from narrow polymetamorphic belts formed over this period.
The supercontinent Rodinia assembled during the late Stenian probably completing its formation in the Tonian then breaking up during the Tonian period.
The Gamburtsevs mountain range in Antarctica began forming.
Mackenzie Large Igneous Province forms 1,270 million years ago. It's a major Mesoproterozoic large igneous province of the southwestern, western and northwestern Canadian Shield in Canada.