It is one of several changes to the historic site that visitors will find for the Summer 2001 season, according to site manager Tom Sanders. The additional hours will give visitors the opportunity to see the petroglyphs at their most visible. Trail markers and site staff help visitors locate and better understand the petroglyphs. Guides not only interpret the site's human history, they also are knowledgeable about its geology. Visitors see ancient bedrock that once was sandstone formed from the sandy bottoms of braided rivers, then changed by heat and pressure into quartzite.
Scientists attribute the shades of red to the presence of iron as the rock formed.
Visitors also learn that in Dakota tradition, the colors are the essense of an important historic event. The site has numerous types of prairie flowers and grasses that create an ever-changing pattern on the landscape according to the season. Among the flora is the prairie bush clover, a federally listed endangered species that grows at the historic site as in no other known site in the world. Deep-rooted tall grass and prickly cacti also can be found. Theme programs on these and other aspects of the site will be held at 2 p.m. daily during June, July and August.