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Rio de Flagg at Picture Canyon. Photo by Tom Bean.

Dr. R.F. Holm receives coveted 'Best Popular Guidebook Award 2020'

We are delighted to note that Dr. Richard F. Holm's (Northern Arizona Univ.,  retired) Rio de Flagg trail guide has been awarded the prestigious ‘Best Popular Guidebook Award’ from the Geoscience Information Society for 2020. ‘Geology of Flagstaff and Geologic History of Rio de Flag, Northern Arizona, with Trail Guides to Geology along Rio de Flag’ was published by the AZGS in June 2019 as volume #23 in our Down-to-Earth series. Rio de Flag is part of the regional drainage system in northern Arizona. Since published 16 months ago the free, online trail guide has been viewed more than 3,000 times.

The Geoscience Information Society began its tradition of awarding excellence in guidebooks production since 1990. A complete list of awardees, and in some cases URL links to free, online guidebooks is available at its website

From Dick Holm’s introduction of the Rio de Flag field guide. “This geology and trail guide is for anyone who likes to walk, be outdoors, and is interested in the geology in and around Flagstaff. The geologic story is focused on Rio de Flag because it flows through Flagstaff, touches or passes by all of the geologic elements in the city, and is accessed easily. The origin and history of the Rio, and how geologic structures and deposits have controlled and changed its watercourse through time, are presented with extended text, maps, photographs, and trail guides... Trails along Rio de Flag include segments of the Flagstaff Urban Trails System (FUTS), local unofficial social trails used for convenience by people and animals, and the Flagstaff Open Space Program trails at Picture Canyon Natural and Cultural Preserve."

Figure. (L) Elden Mountain a Pleistocene-age exogenous dacite dome overlooks the northeast side of Flagstaff, Arizona (Fig. 10, p. 22). (R) Cartoon illustrating the formative processes of Elden Mountain (Fig. 36, p. 49).

Mt Elden dacitic dome, Flagstaff, Arizona

Mount Elden


We congratulate Dr. Holm on an award well-earned. We thank GSIS Guidebooks Committee Chair Dwight Hunter for alerting us to GSIS selection of Dr. Holm’s Rio de Flagg guidebook for their 2020 ‘Best Popular Guidebook Award’.

Citation.  Holm, R.F., 2019, Geology of Flagstaff and Geologic History of Rio de Flag, Northern Arizona with Trail Guides to Geology along Rio de Flag. Arizona Geological Survey Down-To-Earth #23, 70 pages.