Dan at Canyonlands National Park, Utah, 2023

Visitors from the Chinese Academy of Sciences in the Black Hills with Dan, 2019

Dan at the Grand Canyon, 2019

Dan and two grad students collecting microbe samples from the 4100 ft level of the SURF, 2022

Axis of Sidling Hill syncline in road cut on I-68 in Maryland, 2016

Dan at Arches National Park, Utah, 2023

Brush growing on the Great Unconformity contact in Alcova Reservoir, WY 2018 Top photo: Halemaʻumaʻu Crater on Kilauea in Hawaii, 2021