This dead juniper tree is near Barker Dam reservoir. Rock piles and domes of exfoliating granitic rock crop out throughout the Wonderland of Rocks area that encompasses Barker Dam Reservoir. The granitic rock intruded in the Mesozoic area (between late Triassic to early Cretaceous time). Pieces of pre-Mesozoic age rocks ranging in size from small pebbles to city blocks are locally incorporated into the granitic intrusions throughout the park area. These rocks, called xenoliths, are typically dark in color and consist of minerals that melt at higher temperatures than that the quartz and feldspar minerals that crystallize in the magma that formed the granitic rocks.