Bedrock Basin Sites
(click the images below for more detail)
Indian Bathtubs - Curious deep basins called "Indian Bathtubs" are found on several granite outcrops in Mountain Home State Forest. Excellent examples of these can be seen at the Sunset Point Picnic Area, which just off the main road about two miles west of Balch Park. Although these "bathtubs" resemble giant Indian mortar holes, no one knows for sure how they were formed. However, regular arrangements of bathtubs, similarity in size, and a close association with bedrock mortar holes and Indian artifacts strongly indicates a man-made origin. A 2008 study by the U.S. Geological Survey concludes that the bathtubs are indeed man-made, and were created by repeated grinding, in conjunction with building hot fires in the basins to weaken the rock and facilitate grinding. These features were probably made by Indians who frequented the area when Mountain Men and miners first began arriving. The Yaundanchi tribe of the Yokuts, and the Tubatulabal (Pitanisha) and Balwisha (Potwisha) bands of the Paiutes, also known as the Monache, all frequented this area, and any of them may have made these strange archeological wonders.
Bedrock Basins and Mortar Holes at Sunset Point (Mountain Home State Forest)
Salt Basins - There is also a site just above the Salt Springs Reservoir on the Mokelumne River where there are bedrock basins on granite bedrock that are very similar to the ones at Mountain Home State Forest. These features were also studied by the USGS, and they concluded that these basins, which tend to be larger than the Mountain Home ones, were also manmade. The USGS concluded that the Salt Spring Reservoir basins were used by Native Americans to collect salt water from a nearby salt spring that was almost as salty as sea water. They would let the water evaporate off in the basins, then collect the salt residue that was left behind. This left them with a valuable trade commodity that was used to flavor and preserve foods. There are two 2009 USGS publications that deal with this archaeological site, one on the manmade salt basins, and a companion study on the associated salt spring.
Bedrock Basins (for salt harvesting) above Salt Springs Reservoir (Mokelumne River)