These landscapes are the product of many natural forces acting on a variety of rock types during long or short intervals of geologic time. Each group of rocks records a chapter in the geologic story of the region. Other chapters can be read from the tilting, folding, and breaking of the rocks. The latest episodes are written on the face of the land itself. A motorist’s view Most park visitors first see the Teton peaks from the highway. Whether they drive in from the south, east, or north, there is one point on the route at which a spectacular panorama of the Tetons and Jackson Hole suddenly appears. Part of the thrill of these three views is that they are so unexpected and so different. The geologic history is responsible for these differences. _View north._— Throughout the first 4 miles north of the town of Jackson, the view of the Tetons from U. S. 26-89 is blocked by East Gros Ventre Butte. At the north end of the butte, the highway climbs onto a flat upland at the south boundary of Grand Teton National Park. Without any advance warning, the motorist sees the whole east front of the Teton Range rising steeply from the amazingly flat floor of Jackson Hole. From the park boundary turnout no lakes or rivers are visible to the north but the nearest line of trees in the direction of the highest Teton peaks marks the approximate position of the Gros Ventre River. The elevation of this river is surprising, for the route has just come up a 150-foot hill, out of the flat valley of a much smaller stream, yet here at eye-level is a major river perched on an upland plain. The reason for these strange relations is that the hill is a fault scarp (see fig. 16A for a diagram) and the valley in which the town of Jackson is located was dropped 150 feet or more in the last 15,000 years. On the skyline directly west of the turnout are horizontal and inclined layers of rocks. These once extended over the tops of the highest peaks but were worn away from some parts as the mountains rose. All along the range, trees grow only up to _treeline_ (also called _timberline_—a general elevation above which trees do not grow) which here is about 10,500 feet above the sea. To the southeast and east, beyond the sage-covered floor of Jackson Hole, are rolling partly forested slopes marking the west end of the Gros Ventre Mountains. They do not look at all like the Tetons because they were formed in a very different manner. The Gros Ventres are folded mountains that have foothills; the Tetons are faulted mountains that do not. Figure 3. _The Teton landscape as seen from Signal Mountain._ [Illustration: A. _View west across Jackson Lake. Major peaks, canyons, and outcrops of sedimentary rocks are indicated by “s.”_] [Illustration: B. _View northeast; a study in contrast with the panorama above._]