The mapped area represents the eastern three-fourths of the Malad Summit Quadrangle, Idaho. It lies mainly in the Bannock Range of southeastern Idaho. The northern and southern margins of the area are 25.5 miles and 17.0 miles, respectively, north of the Idaho-Utah State Line. The Caddy Canyon Formation of Late Precambrian age is the oldest exposed stratigraphic unit. The youngest unit, exclusively of Precambrian age, is the Mutual Formation. The Brigham Formation is considered to be of Late Precambrian to Early Cambrian(?) age. Younger formations of Cambrian to Silurian age are present. The Precambrian units, as well as the Brigham, consist chiefly of quartzite. Younger Paleozoic units are primarily limestone and dolomite. The Precambrian and Paleozoic units are unconformably overlapped by the Wasatch and Salt Lake Formations of Tertiary age. A major thrust fault is widely exposed in the mapped area. It places various formations of early Paleozoic age in thrust contact with the Brigham Formation. Several minor thrust faults are also present. The thrust faulting is related to the Laramide orogeny which was active in western United States from late Jurassic into Eocene. Normal faults, in the mapped area, trend generally north-south x and east-west. The north-south faults, characteristic of the Basin and Range province, are responsible f or most of the relief in the area. The normal faulting began as early as Oligocene and has continued intermittently to the present.

Thesis (M.A.)--Brigham Young University. Dept. of History.

The west central part of the Malad Range is located in south-eastern Idaho. This area was the site of thick marine deposition in the early Paleozoic period. In the Tertiary and Quaternary periods continental deposition occurred, covering the Paleozoic rocks. Quartzite and shale units of the Brigham Quartzite are found near the base of the Cambrian section. Carbonate with shale interbeds is found in the middle and late Cambrian units. Limestone and silty limestone are found in the early and middle Ordovician time overlain by the middle Ordovician Swan Peak Quartzite. The Laketown Dolomite includes units of late Ordovician and Silurian age. Paleozoic units younger than Silurian and and Mesozoic units are not found in the mapped area. Red conglomerates mark early Tertiary deposition, and water-lain tuff, fresh-water limestone, conglomerate and sandstone are of middle and late Tertiary age. Tertiary-Quaternary rocks, found in the mapped area, are composed of deposits of boulders resting on older Tertiary and Paleozoic rocks. These deposits show rough polygonal structures and stone stripes. Quaternary deposits are composed of sediment from the Late Pleistocene Lake Bonneville and Quaternary alluvium. Northwest-trending faults, northeast-trending faults, and north-trending faults are found in the mapped area, with northwest-trending faults predominating. The northwest-trending faults are high-angle faults and have resulted in Tertiary rocks being faulted against lower Paleozoic rocks. Northeast-trending faults are roughly parallel and predate the middle and late Tertiary rocks. North-trending faults are high-angle faults involving both Paleozoic and Tertiary rocks. One northwest-trending fault has evidence of horizontal movement. The structures are assigned to three periods of movement: 1. early Cretaceous to early Tertiary, 2. late Tertiary to middle Tertiary, 3. middle Tertiary to Recent.

The central part of Clarkston Mountain is located in northcentral Utah in the southern part of the Malad Range. It is northwest of Clarkston, Utah. The mapped area measures 2.5 mi. in the north-south direction and 6.5 mi. in the east-west direction. It is within the Basin and Range Province. The Ute Formation of Middle Cambrian age is the oldest exposed stratigraphic unit. Other Cambrian units, in ascending order, are: Blacksmith Formation, Bloomington Formation, Nounan Formation, and St. Charles Formation. These units consist predominantly of limestone, dolostone, and shale. Units of Ordovician age include the Garden City Formation and the Swan Peak Formation. They consist of limestone and orthoquartzite, respectively. The youngest Paleozoic unit is the Fish Haven-Laketown Formation of Ordovician-Silurian age. It is dolostone. Units of Quaternary age include colluvial deposits, Lake Bonneville Group, and alluvial deposits. West-dipping, low-angle normal faults generally trend north and northwest. They were originally thrust faults formed during regional compression. A bedding-plane thrust fault separates the Bloomington and Nounan Formations. Later reversed movement on the west-dipping, low-angle thrust faults changed the stratigraphic relationships across these faults to those characteristic of normal faults. High-angle normal faults trend northwest, north, and northeast. Major normal faults extend along the western and eastern sides of Clarkston Mountain and are responsible for the present topographic relief. The structural features of the mapped area are the result of two major tectonic events. The Sevier orogeny produced eastward directed thrust faults. It began in Late Jurassic and ended in early Eocene. Basin and Range normal faulting caused reversed movement on west-dipping thrust faults, formed by the Sevier orogeny, and also produced many high-angle normal faults. It began in early Eocene and has continued into historic time in the region.

Rocks of Paleozoic, Tertiary, and Quaternary age are represented in the northern part of the Malad Range. The Paleozoic rocks are represented by thirteen formations that are characterized lithologically by quartzites, shales, and carbonates. The oldest formation in the mapped area of Paleozoic age is the Brigham Formation, and the youngest formation is the Jefferson Formation of late Devonian age. The rocks of Tertiary age are conglomerates, shales, and limestones and are represented by the Wasatch Formation, the Salt Lake Formation, and boulders. Quaternary rocks include sediments of the Lake Bonneville Group and alluvium. The faults in the mapped area were formed during two periods of movement. The east-west-trending faults, northeast-trending faults, and northwest-trending faults are a consequence of compressional forces during Laramide orogenic activity. The north-south-trending faults were the result of Basin and Range block faulting during middle and late Tertiary times.

The Malad Valley is geographically located in a unique position in the Pacific Northwest. The Bear River and its main affluent, the Malad River, are the only rivers in the Pacific Northwest that drain into the Great Basin, whereas the other streams and rivers of the states of Washington, Idaho, and Oregon empty eventually into the Pacific Ocean. It is also characterized for being the northern end of prehistoric Lake Bonneville, and eventually it was through this valley that an outlet opened to drain the lake. The soil deposits from this lake left a fertile valley, capable of producing most crops found in this region.Circumstantial evidence gives indication of many mountain men trapping and exploring in this valley. One account credits Donald McKenzie with naming the Malad River in this valley in 1819 because the flesh of its beaver, when eaten, induced illness in the party. This account, the author found, did not pertain to the Malad River, tributary of the Bear River, but to the other Malad River which is a tributary of the Snake River, over 200 miles distant. Other evidence promotes the idea that the river was named Malade because French trappers became ill from drinking the water. The two Malad Rivers were named for the same reason. Evidence supports the idea that there were two rivers which caused the same ailment when the beaver flesh was consumed. The tributary of the Snake was named by McKenzie and the fur trappers merely referred to another Sick River (Malade), the tributary of the Bear River.