Many of the cliff faces of the Wingate are darkened or blackened by desert varnish—a natural pigment of iron and manganese oxides, silica, and clay.[19] Dinosaurs left their footprints in the sands of the Wingate in parts of the Colorado Plateau, but no tracks or fossils have yet been found in this formation in or near the Monument. The Rains Came The arid climate of Wingate time was followed by a wet period, when streams from the northeast gradually covered the sand dunes with mud, sand, and some gravel. The sand and gravel of the stream channels were cemented into hard sandstone and conglomerate, and the mud of the flood plains hardened into red and purple siltstone and mudstone. The resulting Kayenta Formation makes up the bench between the two cliffs upon which the Visitor Center, campgrounds, and most of scenic Rim Rock Drive were built. Here, nature was kind, for this gently sloping bench was an ideal place to build the road from which to look down into the deep chasms. The Kayenta also caps the broad mesas between the canyons. It is about 350 feet thick in eastern Utah, only 45 to 80 feet thick in the Monument, and it is absent altogether not far east of the Monument. The reasons for the eastward thinning and ultimate disappearance of the Kayenta and some younger rocks are given in the next section. [Illustration: RED CANYON, looking northeast toward Grand Junction from Red Canyon Overlook. Dark notch at the bottom of the northeast end of the canyon is known as the Gunsight. Linear feature in the Grand Valley beyond is the Denver and Rio Grande Western Railroad. Prominent point near middle of Book Cliffs is Mount Garfield (Fig. 25). Battlement and Grand Mesas form left and right skylines, respectively. Dark green bush in right foreground is Mormon Tea. (Fig. 12)] [Illustration: THIN BEDDED KAYENTA FORMATION protecting underlying cliff of softer Wingate Sandstone. Rim Rock Drive is on bench of the Kayenta close to thinner cliff of Entrada Sandstone in background. Looking northwest from a point northeast of Monument Canyon View. (Fig. 13)]