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Show inzz EEiEEi" . i.'ofi ;-.-s.:!f h C ro::; Soct i! , 1 1 if .3 s t e 111 i'fah. Park Service Report flloab Was Once Buried Under Ikm Of Sediment; Geoloqisfs Te!l Us Considering today, wilh trips to the moon r beyond, supersonic aircraft and the changing parameters with which we measure time and space, it is still difficult to imagine that Moab was once buried under at least one mile of rock. That is more than 5,030 feet of rock that isn't here anymore. It is alright to talk about (flood-swollen streams carving millions of tons of sediment in- thebr load, but it is hard to conceive con-ceive that all the rock which once buried Moab is gone. Look at a north-soulih cross section of southeastern Utah. The ground profile is like a set of stairs. The steps climb to the north. Picture each step as representing a major set of cliffs. The Bock Cliffs north of Crescent Junction Junc-tion are a good example of one such set of stairs. Now the Books weren't always where they are today. We just happen to be living on the earth at ithe same time as they are at their present location. lo-cation. Confusing? Logic and fact indicates that the Book Cliffs once projected southward south-ward over this country, covering cov-ering our area with a thick blanket of rock. At any one time in the geological past, each set of -stairs in this profile pro-file extended just a little fur-thur fur-thur south from the next higher steps. Today, northward north-ward erosion nips at each step and moves it further from us. By the same token, steps to the south are working work-ing toward Moab. Someday Moab will have to move. Or the town will have dropped to the 'bottom of the step when the step reaches here. But Moab may resit easy, it will happen to you folks in Monticello first. This stair step profile is the same thing you see in a typical canyon in this country, coun-try, only it is on a much grander scale. As each canyon can-yon erodes headward, so, on a regional basis, do the overall over-all rock layers. What triggered thi sero-sion? sero-sion? Many factors are involved invol-ved in the answer. First, erosion ero-sion has been going on ever since the earth was born. We know that this entire Canyonlands Canyon-lands country is part of the Colorado Plateau uplift. In addition, secondary, minor uplifts called the Monument Upwarp. Since we are north of the center, the rocks have a regional north dip. True, salt anticlines and the La-Sal La-Sal mountains locally interrupt inter-rupt this regional north dip, but the overall trend is the same. In any of the earth's crust, the first part of the uplift to be eroded is the highest point. From there, erosion works away from the center of the positive area toward the flanks. The center of the Monument Upwarp is south of Monticello, almost parallel paral-lel with Blanding. There erosion ero-sion first began, then working work-ing northward in steps, stripping strip-ping off layer after layer. We have our local, fascinating fascin-ating geology in this immediate imme-diate area. We are also part of a regional and countrywide country-wide picture. This applies to rocks as well as to people, pcpuloaions and environments. environ-ments. We must look beyond our immediate area to solve the geological riddles, as we must also do to solve our environmental en-vironmental problems. |