A photo of several bird nests

Bird nest in an exfoliation cavity in the Painted Rock alcove. Note the cross bedded character of the sandstone in the upper part of the image. Cross beds reflect deposition of sand under the influence of marine currents. The current direction was to the right. These sediments of the Painted Rock Member of the upper Vaqueros Sandstone (named for this location) were deposited nearly 20 million years ago when the region was submerged under a shallow inland bay that flooded the southern San Joaquin Valley region (Dibblee, 1973). The sediments have since been tightly cemented by mineral precipitates from groundwater.