In the summer and fall they moved inland to harvest one of their staple foods, acorns, which were very abundant throughout Big Sur. They gathered acorns from the Black Oak, Canyon Live Oak and Tanbark Oak, primarily on upper slopes above the narrow canyons. They first soaked the acorns in running water to leach the bitter tannin from them. They then ground the acorns using a mortar. Over many years they hollowed out bedrock mortars in granite rock outcroppings that they used to grind plant seeds and acorns into flour. A large bedrock mortar is located in Apple Tree Camp on the southwest slope of Devil's Peak, north of the Camp Pico Blanco. More than across, the boulder contains a dozen or more deep mortar bowls worn into it over several generations. Other mortar rocks have also been found within the Pico Blanco Boy Scout camp at campsites 3 and 7, and slightly upstream from campsite 12, while a fourth is found on a large rock in the river, originally above the river, between campsites 3 and 4. Several Esselen mortars are located in boulders near Clover Basin Camp in Miller Canyon. Once ground, they cooked the acorns into a mush or baked as bread.