Streams from higher lands to the south brought in mud, silt, and sand that piled up hundreds of feet thick over thousands of square miles, including the Monument. These sediments were later compacted into the brightly colored siltstone, mudstone, sandstone, and limestone now known as the Morrison Formation. The colors are about the same as those of the Summerville. Algae and other microscopic organisms extracted calcium carbonate from the lake waters, and when they died this material settled on the lake bottoms to make limestone. The soft siltstone and mudstone of the Morrison Formation weather rapidly into steep or fairly steep slopes, but the harder beds of sandstone, most of which are in the lower third of the formation, known as the Salt Wash Member, are sculptured into bold ledges or low cliffs. The generally softer upper two-thirds of the formation is called the Brushy Basin Member. The Morrison is best exposed in and southeast of The Redlands, where the bare rocks are carved into badlands like the famous ones of South Dakota. Both the Fruita Canyon and No Thoroughfare Canyon approaches to the Monument pass typical badlands in the Morrison. The entire 600 feet of this formation is best seen in the high bluff on the east side of the mouth of No Thoroughfare Canyon (fig. 21). [Illustration: MORRISON FORMATION, on east side of mouth of No Thoroughfare Canyon. Forty feet of Summerville Formation at base is concealed by slope wash, but underlying white- and salmon-colored members of Entrada Sandstone are clearly exposed at lower left. Protective caprock at upper right is lowermost sandstone of Cretaceous Burro Canyon Formation. Upper two-thirds of Morrison is typical of the Brushy Basin Member; lower one-third is not typical of the Salt Wash Member, which generally contains more and thicker lenses of sandstone, some of which are just around the corner to the right. Mesa on left skyline is above Serpents Trail in the Monument. Looking west from Little Park Road. See also figures 55 and 60. (Fig. 21)] In parts of the Colorado Plateau southwest of the Uncompahgre Plateau, the sandstone lenses in the Salt Wash Member of the Morrison contain uranium and vanadium ore associated with carbonaceous matter, including coalified wood. No ores have been found in or near the Monument presumably because such carbonaceous matter, which helped precipitate the ores, is lacking on the northeastern side of the Uncompahgre Plateau.