Around the world, certain landscapes and geological formations have special qualities that make them stand out from their surroundings. Many cultures feel such places have spiritual significance. To American Indians, rock formations emerging from the earth provide a link between the physical and spiritual worlds. Such places are often chosen to record visions, events, stories or maps.
Jeffers Petroglyphs is one of those special places, both for visitors and American Indians. To the contemporary American Indians who live in and around the state, it is a very sacred, spiritual place.
Scholars believe that ancestors of American Indians first made rock carvings, or petroglyphs, on this outcropping about 7,000 years ago. Some of these carvings may have been created as recently as 150-250 years ago. Among the earliest carvings here are images of bison and atlatls, or throwing sticks. Atlatls and darts were used to hunt bison before the bow and arrow were developed 1,200 years ago. These symbols, along with other images carved on the rock, such as thunderbirds and turtles, remain important in American Indian culture.
The carvings of deer, bison, turtles, thunderbirds and humans are more than art or depictions of the natural enviroment. They are important cultural symbols of the complex communities that inhabited the prairies of southwestern Minnesota and still thrive today.
Rock
Viewed from the south, a pink rock face emerges from a sea of green. Fifty yards wide and 300 yards long, this rock seems to float on the native and recreated tallgrass prairie. The rock is part of a 23-mile ridge that extends across Cottonwood County. Called Red Rock Ridge, it is a series of quartzite outcroppings that intersects the southeastern edge of what French explorers called the "Coteau des Prairies." The Coteau, meaning hill, extends from Rutland, North Dakota, to Jackson, Minnesota. The Red Rock Ridge is about 250 yards wide and up to 50 feet higher than the surrounding fields. The rock that is located here is called Sioux quartzite; it is part of the quartzite deposit found near the western border of Minnesota at Pipestone National Monument. The quartzite at Jeffers is one of the oldest bedrock formations in Minnesota, deposited as sand more than 1.6 billion years ago. It is metamorphic rock, meaning it was formed by enormous heat and pressure from deep in the earth. The outcropping was exposed by the wearing action of time. Its color varies from white to red to lavender-brown or reddish purple. Geologists have determined all these colors are caused by an iron oxide film surrounding grains of quartz sand.
This area was at the edge of a shallow sea that covered thousands of square miles. Over and over rivers carried sand from land formations to the sea forming an alluval fan or delta-like formation. This delta formed ribbons of braided rivers that periodically flooded, depositing silt on top of sand bars. Also, the sea advanced and then retreated, each time depositing sand, silt and organic materials. This activity lasted for 150 million years. The quartzite formation was covered by later formations whose great weight supplied the pressure and heat needed to first turn it to sandstone and then to quartzite. After being covered by succeeding layers of rock through the ages, it was exposed again by the wearing action of water, ice, wind and plants. While looking at the rocks notice the deep scratches left by glaciers when they pushed their way south 14,000 years ago.
Prairie
Minnesota is at the northeastern edge of a tallgrass prairie that once covered 400,000 square miles of North America. Today, less than one percent of that prairie remains. Of the 80 acres at Jeffers Petroglyphs, 33 are native prairie and the other 47 are one of the first prairie recreations in Minnesota. Like all prairies, this landscape is a mixture of flowers and grasses. More than 200 species of prairie plants are found here, some of which are very rare. A federally-designated threatened species, Prairie Bush Clover, thrives at Jeffers Petroglyphs.
This grassland is unique in other ways. Prairies are classified as wet, mesic or dry. Because of the rock formation, all three types are found at Jeffers Petroglyphs. Wet prairies have considerable moisture, and the amount of moisture in mesic prairies falls between the other two. Near the rock outcropping, the soil is shallow and dries out quickly, creating an enviroment perfect for plants adapted to the drier plains of the American West. Here you will find prickly pear cactus, buffalo grass and little bluestem. Because the rock face sheds water and concentrates it into a single area, a wet prairie enviroment dominated by cordgrass and sedge is also present. However, the prairie at Jeffers is primarily a mesic prairie, ruled by big bluestem and Indian grass that grows up to eight feet high.
The prairies in this region developed during a warm and dry period 9,000 years ago, a few thousand years after the last glaciers receded from the area. Prairie grasses and flowers adapt to these conditions by forming extensive underground root systems. With this adaptation, the prairie was able to survive fires, which were sometimes started on purpose by people to draw bison to the richer, tender grass that grows in after a fire. During wet years, these fires kept water-hungry trees from taking over the grasslands.
In the 1960s, local residents recognized the cultural and enviromental value of the site. They cleaned it of fieldstones and debris, then identified and recorded the carvings and plant life. In 1966, the Minnesota Historical Society purchased the site with the hope of providing knowledge of and appreciation for the history of the rock carvings, the enviroment in which they are found, and the people who made them.
Almost two billion years of history are recorded on the rocks here. You can see fossilized sand ripples and mudflats that turned to pink quartzite 1.6 billion years ago and deep scars left by the mile-thick Des Moines Lobe glacier as it scraped the rock outcropping on its way south 14,000 years ago.
More detailed information including directions, hours of operation and entrance fees can be found here: visit link.
To log a find on this earthcache please gather the necessary information to answer the following questions as you tour the site, then send your answers to the cache owner listed near the top of this page; click on their name, then either the "send e-mail" or "send message" links:
1. What present-day natural area of the U.S. did this area once closely resemble?
2. According to Dakota oral history why are the rocks the color they are?
3. Estimate the angle (in degrees) of the rock face before you at the posted coordinates. Do not post your answers in your log. All questions can be answered by touring the site, available year-round.
Per EarthCache guidelines photos are not a requirement but any you may decide to include will be appreciated. Information in this listing was obtained from the Minnesota Historical Society, the Jeffers Petroglyphs visitors guide and interpretive center, as well as the site itself.
Thank-you to the site manager and staff at Jeffers Petroglpyhs for their cooperation in developing this EarthCache.
This is considered a sacred site, please show your respect and treat it as you would your own church or place of worship. Stay on the marked trails and do not attempt to touch the images, make rubbings or otherwise disturb the rock surfaces. Please do not pick the wildflowers or other plants. Please do not smoke on the trails, and deposit any litter in the garbage cans provided. Please do not take dogs onto the trails or on the roped path at the carvings. The site/interpretive center is open Memorial Day through Labor Day and requires a small fee to enter. During the fall, winter, and early spring the carvings may still be accessed by taking the trail around the south side of the interpretive center.
