National Geographic : 1978 Jul
the Grand Canyon its unique form, occur mostly on the north side of the river. They were not formed, as the Cracked Earth Soci ety long maintained, when an uplift split the earth like a cake that rose too fast. There's a logical explanation. Less mois ture falls on the south side, and the plateau there slopes away from the rim. The Kaibab Plateau on the north slopes toward the river, dropping more water from a higher eleva tion and thus causing headward erosion to develop faster. Streams, seeking paths of least resistance, often follow fault lines in the earth-as pa per tends to tear along a crease. The steeper the slope of the stream drainage area, the deeper and longer the side canyon erodes, excavating vast amphitheaters and, where canyons meet, leaving behind the pinnacles. Preston Swapp, a young packer on the 1937 Shiva expedition, still lives nearby and until recently grazed cattle on national forest land in Kanab Canyon. Last fall Swapp was forced to suspend his operation. He told me why. "The Forest Service came in and did a study. Said we were overgrazing." "Were you?" I asked. "No." He maintained that the Forest Service study team had picked one of the driest peri ods since his father started grazing cattle here in 1906 to do its survey. Preston, a quiet, well-tanned cattleman of 64 years, said that cattle grazing was once an impor tant industry here, but is now dying out. Upper Kanab Canyon is being studied as a possible addition to the park. "They're trying to run us out," Preston complained. "They're taking away a man's rights. They don't know what this country will produce. If it isn't grazed, trash plants such as blackbrush will take over the land. Those cattle don't compete for food with A riffle of limestone polished like marble (above, left) seems a mirror image of the rushing water that shaped it. A catcher's mitt of a rock (left) holds a stone that, when the water rises again, will resume grinding the pocket. Deer Creek (right) has exposed a laminate of sandstone as it takes the easiest course to river level.