Wednesday, April 9, 2014


Geologic road logs are some of the most useful tools field geologists and rockhounds have at their disposal.  These logs describe geologic features and stratigraphy, at specific mileages, that are visible along the road in question.  In the pre-electronic age most road logs were printed in guidebooks published by various geological societies (and these remain a wealth of information so check at your local academic library).  I have  found these roads listed below useful and interesting as I make annual visits to the Tucson "show."

Rockhounds take note: as usual, be careful, take the necessary precautions when traveling, do not trespass on private land, and know the local collecting regulations.

The road log describes the geology from Flagstaff, located in the pine trees of the Colorado Plateau, down elevation through the Transition Zone, and into the Sonoran Desert of the Basin and Range.

Monument Valley in the northern part of Arizona occupies a prominent place on many travelers’ bucket list.  The road logs follow Jurassic and Cretaceous rocks exposed on the mesas and in the drainages.  The bonus exposures include the numerous igneous rocks called diatremes.

Readers will need to locate this web site then click on the hot link Guidebook 4-Highways of Arizona.  Although this log is about 40 years old, it gives a nice tour of the Apache Trail from the city of Apache Junction north by the Superstition and Goldfield Mountains to the campground and marina at Canyon Lake.