The Rimrocks or "Rims" are formations of geological rimrock sandstone that outcrop in Billings, Montana sectors.
Around 80 million years back, the area of Billings metro was the Western Interior Seaway shore, a sea that presently meets the Gulf of Mexico to the Arctic North. Sediment and sand present in the sea get deposited across the shoreline. As time passing, the sea rises and drop leaving behind a deep sand layer. In millions of years, the sand turns into the sandstone, which makes the rims, and termed as Eagle Sandstone. Click here for more.
Million years back, a river larger as compared to the presently Yellowstone River started cutting a canyon into the Eagle Sandstone valley floor, and develop what today is famous on the name of the Rimrocks. The river is still dividing into the valley floor. It is visible at the Sacrifice Cliff base and the Briarwood Mountain Northern Edge in the South Hills.
The border north of North Rims of the Shiloh, Central-Terry, West End, Downtown Core, and North Park city's sectors. The East Rims border of the Downtown core's eastern edge, the South Hills and Brierwood city sections. Due to the Heights and Lockwood sit on top of the Rimrocks first rise. Do visit this attraction as well.