March President’s Letter

By Rob Diedrich

The Atlas That Changed RMAG

What is it about geologists and maps? I can’t help noticing the variety of maps I’ve seen on the walls of geo-colleagues during Zoom calls. One of my associates has a replica of William Smith’s 1815 geologic map of the British Islands framed on his office wall and easily seen over his shoulder during our online chats. This is The Map that Changed the World, according to Simon Winchester’s 2001 book, and is considered to be “the first true geological map of anywhere in the world.”

For geologists, a map tells a story. We visualize the contours on topographic maps three-dimensionally as hills, mountains and valleys springing out of a flat piece of paper. We become detectives piecing together clues about an area’s geologic history when we overlay surface formations onto topographic maps, creating a geologic map. Most of us developed our mapping skills during geology field camps. I have fond memories of mapping the Paleozoic section near Molas Pass. Some of our mapping areas were riddled with test pits dug by miners looking for silver and gold. These pits were often located in areas of mineralization associated with faulting, providing clues to look for possible offsets in the strata and a fault line to sketch on our maps.

Thinking about the science and art of map making brings me to my RMAG Centennial anecdote for this month. Perhaps the largest and most industrious undertaking in our association’s history was the 1972 publication of The Geologic Atlas of the Rocky Mountain Region, much better known as ‘The Big Red Book.’ And why is it affectionately called ‘The Big Red Book?’ Well, it is RED, and it is BIG, measuring 22 inches long, 18 inches wide, and nearly 2 inches thick. It weighs 14 pounds! The volume, which took six years to assemble, contains 53 papers, countless cross-sections and stratigraphic columns of the Rocky Mountain Region. Most amazing is its collection of beautifully illustrated regional paleographic maps for the major geologic time periods. Today, global paleographic maps are readily available online, however when I began my career as a petroleum geologist in the early 1980’s, I consulted the maps in The Big Red Book often to identify facies trends and to better understand the regional geology of my project areas. Indeed, The Big Red Book has been a requisite reference for Rocky Mountain geoscientists across multiple disciplines and professions for the last half century.

It may be a bit of a stretch to say that ‘The Big Red Book’ is The Atlas that Changed RMAG, but it can be argued that it is our association’s most seminal publication. It’s been a best seller and has had a significant financial impact on RMAG in more ways than one. For those details and other interesting facts, watch for the Centennial Series article by Jane Estes-Jackson in next month’s Outcrop.

Coincidentally, as we celebrate RMAG’s 100th anniversary, we also celebrate the 50th anniversary of The Geologic Atlas of the Rocky Mountain Region. The Big Red Book has long been out of print, but it was digitized in 2006 and the maps were converted to GIS shape files a few years later. In addition to the map collection, the volume contains chapters on physical, historical and economic geology and a fascinating discussion on pioneer geologists of the American West including historic photographs. The digital Book Red Book is available for sale on the RMAG website with a member price of only $50. Why not consider adding this volume to your collection to commemorate the publication’s historic 50 years!