The visitor who looks at the high, rugged peaks of the Teton Range is seeing rocks that record about seven-eighths of all geologic time. These Precambrian rocks are part of the very foundation of the continent and are therefore commonly referred to by geologists as basement rocks. In attempting to decipher their origin and history we peer backward through the dim mists of time, piecing together scattered clues to events that occurred billions of years ago, perhaps during the very birth of the North American Continent. To cite an oft-quoted example, it is as though we were attempting to read the history of an ancient and long-forgotten civilization from the scattered unnumbered pages of a torn manuscript, written in a language that we only partially understand. Ancient gneisses and schists The oldest Precambrian rocks in the Teton Range are layered gneisses and schists exposed over wide areas in the northern and southern parts of the range and as scattered isolated masses in the younger granite that forms the high peaks in the central parts. The layered gneisses may be seen easily along the trails in the lower parts of Indian Paintbrush and Death Canyons, and near Static Peak. The _layered gneisses_ are composed principally of quartz, feldspar, _biotite_ (black mica), and _hornblende_ (a very dark-green or black mineral commonly forming rodlike crystals). Distinct layers, a few inches to several feet thick, contain different proportions of these minerals and account for the banded appearance. Layers composed almost entirely of quartz and feldspar are light-gray or white, whereas darker gray layers contain higher proportions of biotite and hornblende. Some layers are dark-green to black _amphibolite_, composed principally of hornblende but with a little feldspar and quartz. In many places the gneisses include layers of _schist_, a flaky rock, much of which is mica. At several places on the east slopes of Mount Moran thin layers of impure gray marble are found interleaved with the gneisses. West of Static Peak along the Alaska Basin Trail a heavy dark rock with large amounts of _magnetite_ (strongly magnetic black iron oxide) occurs as layers in the gneiss. In some places the gneiss contains dark-reddish crystals of garnet as much as an inch in diameter. Commonly the garnet crystals are surrounded by white “halos” which lack biotite or hornblende, probably because the constituents necessary to form these minerals were absorbed by the garnet crystals. In Death Canyon and on the slopes of Static Peak some layers of gray gneiss contain egg-shaped masses of magnetite as much as one-half inch in diameter (fig. 20). These masses are likewise surrounded by elliptical white halos and have the startling appearance of small eyes peering from the rock. Appropriately, this rock has been called the “bright-eyed” gneiss by Prof. Charles C. Bradley in his published study (Wyoming Geological Association, 1956) of this area.