An erosional unconformity cutting diagonally across the center of the photo due to a glacial advance about 20,000-18,000 years ago separates two sequences of late-Pleistocene tephra layers from Ecuador's Chimborazo volcano. A less prominent unconformity below the light-colored tephra layer at the top of the sequence marks a 16,000-14,000 year old glacial advance. This ~12-m-thick exposure lies on the SW flank.

Photo by Lee Siebert, 2006 (Smithsonian Institution).

This image is made available under the Public Domain Dedication CC0 license, but proper attribution is appreciated.

Galleries: Volcanic Outcrops | Ash Plumes and Ashfall

Keywords: geology | stratigraphy | ash | outcrop | erosion | tephra

Chimborazo