Most of the information we have uncovered talks about this area being underwater eons ago. As the water receded it showed where the erosion had taken place and formed the caves. Also as they were exposed the wind and temperatures took over and further eroded the area and the caves appeared as seen today. Erosion is an ongoing process. Rock slabs still fall to this day from the ceilings. Middle cave is closed off due to a rock slab falling recently. You can still see and read about what is happening.
Above each cave is a large "V" shaped drainage which shows a black stain above each opening. The water runs over this ledge and helps to carve out the existing caves. The dark color is due to minerals washed into each "V" during rainstorms or snow melt.
The geological evolution of these cliffs began approximately 136 million years ago. During what is now call the upper cretaceous period the arm of the ocean extended across this region. Continued shifting of the continent resulted in a recession of the shorelines as ocean currents and tides formed beaches along the raised areas. These shoreline areas were deposits of sand and ocean mud. Through geologic time and the effects of extensive erosion, the resulting 250 to 300 foot deposits of sandstone known as the Eagle Sandstone formation, make up this unique geological formation known as the rimrocks. Evidence of this prehistoric ocean can still be seen in the ceiling of the middle cave, where a large fossilized clam shell is preserved.
These are not "true" caves as most people perceive caves to be but deep hollowed out depressions in the sandstone cliffs. They are deep enough for protection from the elements so ancient peoples soon occupied them. Because of their location they could see for quite aways to watch for enemies coming their way. There was a river for water and numerous plants and berries to subsist their needs.
The most prevalent feature is the pictographs shown on the inside walls of the caves which number three units. Ghost cave, middle cave and pictograph cave are the three units.
The location of the caves allowed the prehistoric hunters to watch the river while their campsites were not visible to intruders. There are posts with numbers along the trail that correspond to number topics in the booklets available at the trail starting point. In 1964 the Pictograph Cave site was designated as a National Historic Landmark by the U.S. Department of the Interior. The Billings Indian commission administered the area briefly before the State Parks Division took over in 1969. Not only were the caves used as living places, but the protected cave walls were also used to record pictures of meaningful events and spiritual topics.
Please follow park precautions , rules and hours.
To claim the cache as a find you must e-mail us with the following information.
1. Tell us, The distance from the cave floor to the ceiling before archaeological excavation was started.
2. For the earth science part,, tell us what the name of the large boulders that look like they have been suspended into the cliffs are called and how they were formed.
3. Tell us the type of soil and how the caves were formed .
FTF Honors go to lakeman for their find on 20 Oct. 2007 at 10:49 am their 1800th find.