Some absolutely gorgeous ~2.7 Ga Banded Iron Formation (BIF) from Soudan, Minnesota.
The rotating silver and reddish layers are hematite and jasper respectively, and these BIFs differ from their Proterozoic counterparts in that they were chemically precipitated.
The outcrop is intensely folded and shows numerous interference patterns, meaning that there are folds that have been re-folded. There likely then was some combination of soft-sediment and tectonic deformation.
Emily Zawacki, Ph.D. 