Rock City, Kansas facts for kids
Quick facts for kids Rock City |
|
|---|---|
Rock City, 2006
|
|
Map showing location of Rock City
|
|
| Location | Minneapolis, Kansas, Ottawa, Kansas, Kansas, United States |
| Elevation | 1,276 ft (389 m) |
| Website | Web Site |
| Designated: | 1976 |
Rock City is a special park in Ottawa County, Kansas. It sits on hillsides that look out over the Solomon River. You can find it about 3.6 miles (5.8 kilometres) south of Minneapolis, Kansas. It's also just over 0.5 miles (0.80 kilometres) west of Kansas highway K-106.
This unique park is famous for its huge, round boulders. These boulders are found in three groups across a grassy area. This area is about 500 meters (1,600 feet) long and 40 meters (130 feet) wide. In total, there are about 200 of these amazing spherical rocks. Because it's so special, Rock City has been named a National Natural Landmark.
A non-profit group owns and takes care of the park. It has a visitor center where you can learn more. There are also picnic tables if you want to eat outdoors. A small fee helps keep the park clean and maintained for everyone to enjoy.
Scientists and explorers have been interested in these rocks for a long time. People like Bell, Gould, and Shaffer studied them. Shaffer was the first to draw maps of where the boulders were located. He also looked closely at what the rocks were made of.
Contents
What Makes Rock City Rocks Special?
The large, round boulders at Rock City are giant "cannonball concretions." Think of them like natural cement balls! They are made of sandstone held together by a mineral called calcite. These rocks are really big, ranging from 3 to 6 meters (9.8 to 19.7 ft) across. The average size is about 3.6 meters (12 feet) wide.
How Big Are These Boulders?
These huge concretions are spaced out, usually 2 to 8 meters (6.6 to 26.2 ft) apart. You can find similar giant concretions in other places too. For example, there are some in a quarry in Lincoln County, Kansas. They also appear in sandstones of similar age in Utah and Wyoming.
What Are the Rocks Made Of?
The boulders are mostly made of sand grains, tightly glued together by calcite. Over 95 percent of the sand is quartz. About 20 percent of the original sand, mostly feldspar grains, has been replaced by calcite. You might also see tiny crystals of pyrite inside. Pyrite often turns into goethite, which is a type of iron rust. Sometimes, there are even smaller concretions trapped inside the larger ones!
The Surrounding Sandstone
The rock around these boulders is much softer. It's a sandy rock that breaks apart easily. It's only weakly held together by a small amount of iron oxide. This softer rock erodes, or wears away, much faster than the hard concretions. This is why the round boulders stand out so much!
The sand that formed these rocks was laid down by an ancient river. This river was part of the Dakota Sandstone formation. This area was once a low, flat coastal plain. The way the sand was cemented, and how it eroded, created the unique shapes you see on the boulders today.
How Did Rock City Boulders Form?
For a long time, people weren't sure how these round boulders came to be. Some thought they were left by glaciers. Others believed they were ancient corals or just regular eroded rocks. But a scientist named Shaffer was the first to figure out they were "calcite-cemented concretions."
The Science Behind Their Creation
Later, scientists like McBride studied the rocks even more closely. They looked at the minerals and the chemical makeup of the calcite. They found that the boulders formed deep underground. Water carrying calcium moved through the sandstone. The calcite then slowly grew and hardened, forming the round shapes.
The materials that made up the concretions came from different sources. These included limestone from the ocean, shells, or even methane from other rock layers. After the concretions formed, the softer sandstone around them slowly wore away. This left the hard, round boulders standing freely, just as you see them today!
Gallery
-
Tree at Rock City
-
A turtle-shaped rock
-
A large, round rock
-
Trees at Rock City
-
Hesperis matronalis growing by a rock in May
-
Looking towards Minneapolis, KS across rippling wheat fields in May
