The first and second rise of the Billings Rimrocks

The Rimrocks (also known as the "Rims") are geological rimrock

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicat ...

formations that outcrop in sections of

Billings, Montana Billings is the largest city in the U.S. state of Montana, with a population of 117,116 as of the 2020 census. Located in the south-central portion of the state, it is the seat of Yellowstone County and the principal city of the Billings Met ...

. Eighty million years ago the Billings metro area was the shore of the

Western Interior Seaway The Western Interior Seaway (also called the Cretaceous Seaway, the Niobraran Sea, the North American Inland Sea, and the Western Interior Sea) was a large inland sea that split the continent of North America into two landmasses. The ancient sea ...

, a

sea The sea, connected as the world ocean or simply the ocean, is the body of salty water that covers approximately 71% of the Earth's surface. The word sea is also used to denote second-order sections of the sea, such as the Mediterranean Sea, ...

that went from the present-day Gulf of Mexico to the Arctic North. Sediment and sand from the sea were deposited around the shoreline. Over time the sea rose and fell leaving behind a deep layer of sand. Over millions of years this sand was compressed into the sandstone the rims are made of. It is known as

Eagle Sandstone The Eagle Sandstone, originally the Eagle Formation, is a geological formation in Montana whose strata date back to the Late Cretaceous. It is a light to brownish gray to pale yellow-orange, fine-grained sandstone. It contains areas of crossbedd ...

. Around a million years ago a much larger river than the current-day

Yellowstone River The Yellowstone River is a tributary of the Missouri River, approximately long, in the Western United States. Considered the principal tributary of upper Missouri, via its own tributaries it drains an area with headwaters across the mountains a ...

began cutting a canyon into the valley floor of Eagle Sandstone, creating what today is known as the Rimrocks. The river still continues to cut into the valley floor. This can be witnessed at the base of the Sacrifice Cliff and the Northern Edge of Briarwood Mountain in the South Hills. The North Rims border north of the Shiloh, West End, Central-Terry, Downtown Core and North Park sections of the city. The East Rims border the eastern edge of the Downtown core, the South Hills and Briarwood sections of the city. Much of the Heights and Lockwood sit on top of the first rise of the Rimrocks. A second rise borders the eastern edge of Lockwood and also runs several miles north of the city and borders northeast sections of the city. The second rise is over 600 feet in places making the total from the valley floor to the top of the second rise over 1,400 feet in places. The tallest single section of the Rimrocks starts at the eastern border of the downtown area with a cliff known as Sacrifice Cliff and extends to the south for roughly 18 miles. This area is known as

Coburn Hill Coburn Hill is located southeast of Billings, Montana in Yellowstone County. Its most predominant feature is Sacrifice Cliffs, part of the Rimrocks surrounding the city. Another feature is several radio and television broadcast towers located on ...

. In the late 1960s, the Concerned Citizens for a Better Billings organized a petition campaign to preserve the Rims in their natural state. When the group's effort's failed, the ''

Billings Gazette The ''Billings Gazette'' is a daily newspaper based in Billings, Montana that primarily covers issues in southeast Montana and parts of northern Wyoming. Historically it has been known as the largest newspaper in Montana and is geographically one ...

'' published an editorial suggesting that the area be preserved as a national monument. The

National Park Service The National Park Service (NPS) is an agency of the United States federal government within the U.S. Department of the Interior that manages all national parks, most national monuments, and other natural, historical, and recreational properti ...

considered the idea, but concluded that the Rimrocks were "of less than national significance."

References

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Cliffs In geography and geology, a cliff is an area of rock which has a general angle defined by the vertical, or nearly vertical. Cliffs are formed by the processes of weathering and erosion, with the effect of gravity. Cliffs are common on coa ...

Geography of Yellowstone County, Montana Billings metropolitan area

See also

References