| 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. |