Rod Benson presented a "Readers Digest Version" of Blaine County's geology

Rod Benson, who grew up in Harlem, was the third presenter in the Blaine County Museum's 2023/24 Off-Season Speaker Series. Benson was a high school science teacher in Helena for 37 years and retired in the spring of 2019. December of that year he began teaching science and coaching archery at Hays-Lodge Pole High School. He said he will be "re-retiring" this spring. The Off-Season Speakers Series is co-hosted by the Blaine County Museum and the Chinook Senior Center.

Benson presented on the geology of Blaine County. Using audio-visuals, photos of local areas and his own drone footage Rod showed the forty-six attendees how various geological eras affected the development of our part of the world and specifically Blaine County. Rod Benson is an avid outdoorsman, having hiked and explored many areas of Montana and the surrounding regions. His forty-plus years of teaching experience and exploring was evident as he took complex geologic phenomena and helped the audience understand why different parts of our area are so varied. Museum Director Sam French said this was the largest audience turnout for this year's speaker series.

Some highlights of Blaine County's geologic history

Grouping earth's several geologic eras in to three main periods Benson explained, with audio visuals, how earth changed over millions of years. He described how the planet's landforms were transformed by multiple glacial periods and through shifting of the "plates" that make up the earth's surface. These shifts in the earth's physical surface, the accompanying earthquakes and volcanoes and glacial interludes shaped how our area now looks. Using photos and drone footage from his own explorations, he explained how various landforms in the immediate area came about.

The results of these dramatic natural events are still evident as one drives through Blaine County. Erratics, the large, random rocks (and sometimes huge boulders) that are on top of the ground or partially buried in fields, were broken off by glaciers that moved through our area. As the glacial period ended and melting occurred the erratics dropped from the glaciers. Benson added, "The melting of the glaciers also scooped out the "kettles," or prairie potholes, common to certain parts of our area." Glacial activity was also responsible for the Milk River's current riverbed location that was once a more northern route of what is now the Missouri River.

Geologic processes also resulted in the deposits of gold that were mined in the Little Rockies in the 1970s-90s. Superheated water, located underground and under pressure, dissolved minerals (gold, as one example) and held them in suspension. When cooling occurred, the minerals settled out and formed solid layers, or veins, that were later mined.

Another major landform in Blaine County that was the result of glacial movement is what locals call the Big Flat. In a narrative for an historical building near Turner, the Big Flat is described as "...an area of about 132,000 acres with rich glacial till soils 20 to 30 inches deep. Homesteaders found plentiful water at only 15 to 25 feet below the surface. The Big Flat developed exclusively as a grain-producing area in comparison to ranching or a combination of grain farming and ranching in most of the rest of the county."

Per Rod Benson the 'island' known as the Big Flat was an area of land that was surrounded by a glacier but not covered by it. When the glacier melted the Big Flat was left. He added, "That gave the Big Flat about a hundred thousand years' head start on creating soil. That's why that soil is so much better than other parts of the county." The glacial activity also helps explain the large underground water impoundment so important to agriculture in the area.

One especially interesting observation Benson made was about Snake Butte, the rock formation visible south of Highway 2 as one drives from the west in to Harlem. From a quote he shared from the presentation: "Snake Butte is the most interesting landform on the Hi-Line-possibly the most interesting one on all of Highway #2 from the coast of Washington to Michigan. It is significant to the Aaniiih and Nakoda people as a sacred site, it played an important role in construction of the Ft. Peck Dam, the geology related to both volcanism and glaciers is VERY interesting and the scenery/wildlife viewing is incredible as well (rattlesnakes, bison, etc.)."

Benson used his drone to take some dramatic photos of Snake Butte. One photo (see attached photo) shows how heat produced liquid rock, or magma. As the magma cooled it cracked into the somewhat geometric columns. Over time erosion removed the less durable sedimentary rock exposing the butte .

Readers interested in learning more about Rod Benson's ramblings around the region will find a lot of information and photos at his blog: bigskywalker.com and can follow weekly updates via Instagram: rodbenson406. Rod also encourages readers who might like to participate in geology-related hikes to follow the Facebook page of "Havre Trails," a local group of hikers.

What's next?

Carl Davis, who was scheduled to make the fourth presentation in the Off-Season Speakers Series during the Harlem Seed Show has had to cancel for the time being. Museum Director Sam French said Davis will likely be rescheduled sometime later this year. For the upcoming presentation at the Seed Show, Austin Haney, who works at the Blaine County Museum after serving as the seasonal ranger at the Bear Paw Battlefield, will be presenting on Friday, March 8. His topic will be "Iron Dreams: Montana and the Pacific Railroad Surveys of 1853." That topic has to do with the Stevens Expedition tasked with finding and mapping the best route for the country's first transcontinental railroad. Haney presented this topic at the first session of the Speakers Series back in the fall. French also announced that videos of the Speaker Series will be available on YouTube, "hopefully in the near future."

Co-hosts Sam French, of the museum, and Ginger Hansen, Chinook Senior Center Director, were asked about the success of the off-season speakers' series. French said she was impressed with the common thread she observed in all the talks explaining, "Through all the presentations I've learned more about just how diverse our county is. The last one by Rod Benson showed our varied geology and how that affected where and how people live in the area." French said there will definitely be a new season of speakers. She added, "We'll be looking at timing to decide if we need a shorter period to offer the events-maybe a fall to December or January to early spring schedule."

Ginger Hansen said she found the presentations wonderful and added, "Our community is fortunate to have them." At the end of the recent presentation Sam French publicly thanked Ginger for her role in making the Off-Season Series events a success and added, "She makes the Center a very welcoming place." The co-hosts seemed pleased with the success of the program and the increasing numbers of guests who are coming to the programs.