One of my favorite places to hike in the Billings area is Zimmerman Park, which is mostly atop the Rimrocks, a cliff formed by sandstone of the Cretaceous Eagle Formation. The Eagle Formation is usually interpreted to be either a barrier island deposit, similar to Padre Island in Texas, or a shallow marine sand bar that ran parallel to the shoreline. The sand was deposited in the Western Interior Seaway, a shallow body of water which stretched across North America from the Arctic to Gulf of Mexico. From Billings, sedimentary rocks become increasingly marine-dominated to the east, and terrestrial to the west.
Here are a few pictures from today’s late afternoon hike:
The Billings Gazette has three short videos on the geology of the Billings, Montana area featuring Rocky Mountain College geology professor Derek Sjostrom:
Geology of the Beartooths — Montana’s highest mountain range (Granite Peak, 12799 ft, 3902 m) has a core of 3.2 billion year old metamorphic rocks.
Geology of the Pryors — The Pryor Mountains (East Pryor Mountain, 8786 ft, 2678 m) south of Billings are formed mostly of blocks of Paleozoic sedimentary rocks.
Geology of the Rimrocks — The Rimrocks are Cretaceous sandstone cliffs on the north side of Billings. The fossils and structures indicate that the Eagle formation formed in a barrier island setting, much like modern Padre Island in Texas.
These are at a very basic level, but I still enjoyed them, and it looks like there are more to come in the series.
WordPress won’t let me embed these videos.
Video from the Billings Gazette: Rimrock boulder destroys video camera (I haven’t figured out to embed this on on my WordPress blog).
Slideshow: Gallery: Falling rocks.
Here’s another video, but it isn’t nearly as good as the “Rimrock boulder destroys video camera” linked to above:
As a teenager I would climb in the cracks between the Rimrocks and the slabs of rock that were slipping away from the cliff at a millimeter per year. Those boulders make nice landscaping for expensive homes at the base of the cliff, but…
Grace and Peace
People like to build in pretty places. In Billings, Montana (where I spent the first eighteen years of my life), there are plenty of big houses along the Rimrocks, a cliff that forms the northern border of much of the city.
Part of the landscaping for these expensive homes is the sandstone boulders, many of which are the size of a bus. One of the hazards, of course, is that those rocks didn’t get to their present locations gently.
From the Billings Gazette: Billings home demolished by falling rocks.
There was a man in the house when the rock hit it, but thankfully no one was hurt.
The house was on Granite Avenue, but the rock was most certainly a piece of Late Cretaceous Eagle Sandstone.
Grace and Peace, and don’t build your house too close to the cliff.