See the context of this sign.

Water and Food

A dependable water source, such as Cottonwood Spring, was curcial to
the Cahuilla Indians, who lived in this region. They could find water-
loving plants important to their diet and it was a good place to construct
a semi-permanent base for food-gathering.

The nature trail continues down into and across the wash, ending at the
site of the bedrock mortars used by the Cahuilla for food preparation. If
you are just beginning this trail at the oasis and wish to learn more about
how the Cahuilla lived off the land, another secion of the trail leads from
north of the parking area to the Cottonwood campground.

Don't miss the rest of our virtual tour of Joshua Tree National Park in 1588 images.