thicknesses of normal sediments. Consequently, the troughs receiving most of the sediments began to form downfolds, or synclines, and the ridges receiving little or no normal sediments began to form huge salt rolls that later were to become the cores of the salt anticlines when finally the ridges too were buried by sediments. Thus, the cross section (fig. 8) shows about 12,000 feet of the Paradox Member beneath the crest of the Salt Valley anticline and only about 2,000 feet beneath the Courthouse syncline. Near the middle of these structures farther to the southeast, all the Paradox Member has been squeezed out from beneath the bordering synclines. [Illustration: GRAVITY ANOMALIES OVER SALT VALLEY, along line _B-B′_ shown in figure 9, and relative densities and shapes of rock bodies beneath. Densities are in grams per cubic centimeter. Gravity values are in milligals, as shown. The standard acceleration of gravity is 980.665 centimeters per second per second; 1 gal is equal to 1 centimeter per second per second, and 1 milligal is one thousandth of a gal. Modified from Case and Joesting (1972, fig. 2). (Fig. 10)] The general shape of the Salt Valley anticline is shown also by cross-section _B-B′_ (fig. 10), taken along the northeast-southwest line _B-B′_ in figure 9, which is based upon so-called gravity anomalies over Salt Valley. The lighter Paradox Member, having an average density of 2.20, has a lower gravitational attraction than the heavier rocks on each side, which have an average density of 2.55. By this time you are doubtless wondering why prominent upfolds of the rocks, such as the Salt Valley anticline and associated Cache Valley anticline and the Seven Mile-Moab Valley anticline, now underlie relatively deep valleys bordered by prominent ridges. The formation of these valleys was not simple and involved many steps extending over a considerable amount of geologic time, as portrayed by Cater (1970, fig. 13; 1972, fig. 4). For a part of the story, let us reexamine the cross section (fig. 8); the rest of the story will be told in the section on “Uplift and Erosion.”