"The fault in the Tucki Mountains that produces Mosaic Canyon consists of mosaic breccia and smooth Noonday formation dolomite, formed in a sea bed 750 to 900 million years ago. After being pressurized and baked at more than 1000 degrees F, then eroded, the resulting rock has startling contrasts of both texture and color. Mosaic Canyon drains more than 4 square miles of the Tucki Range, so it is to be avoided, like all canyons, in flash flood conditions. Rushing water, carrying its load of scouring boulders, has created smooth marbleized waterways out of the otherwise lumpy breccia. Silky surfaces gradually change to rugged lumps from the canyon floor up its walls, reflecting the varying depths of floodwaters. Like other canyons in Tucki Mountain, Mosaic Canyon is alternatively wide and narrow. The wider spots are more numerous, and are broad enough almost to qualify as valleys. Often parties of hikers arrive at these open areas and turn back, figuring that the canyon excitement has ended. With plenty of water and a broad-brimmed hat, you can continue exploring the depths of Mosaic. A long out-and-back day hike up a deep, narrow canyon in the Cottonwood Mountains, with colorful rock formations, petroglyphs, and expansive views of remote backcountry."