Abstract Physiographically and geologically, western Canada consists of three great parts: a core of crystalline rocks forming the Canadian (Precambrian) Shield; a surrounding band of younger, essentially flat-lying, stratified rocks; and on the western side, a rim of highly deformed sedimentary, volcanic, and igneous rocks (Fig. 2C.1, 2C.2, 2C.3). The Canadian Shield has a slightly depressed centre, presently the site of Hudson Bay and Hudson Bay Lowland. The surrounding band of undeformed Phanerozoic rocks forms the Interior Plains on the western margin and St. Lawrence Lowland on the southern margin. These areas are characterized by lowlands, plains, and plateaux, which were substantially modified by glacial action during Pleistocene time. The outer belt of deformed rock forms the magnificent mountainous terrain of the Canadian Cordillera. The classification of physiography in western Canada has evolved since the early writings of A.R.C. Selwyn and G.M. Dawson (1884) and a classic study by R.A. Daly (1912). The physiography of British Columbia was described by S.S. Holland (1964), and that of Canada by H.S. Bostock (1970a,b). These reports have been used extensively for the following summary. As part of the current syntheses of the Geology of Canada, W.H. Mathews (1986) has modified parts of the earlier classification of Cordilleran physiography, basing his study on landsat imagery and recent reports. The physiographic divisions set forth on Matthew’s geomorphic map are used in this section. A more detailed discussion of the geomorphology of the Cordillera may be found in the Cordilleran volume

Abstract Interstate 80 between Elko and Carlin, Nevada, follows the valley of the Humboldt River. The Humboldt drains a 17,000 square mile basin along its 275 mile course, located entirely within the State of Nevada. While barely a trickle of water in late summer, spring floods may swell the river well over its banks. The average annual discharge is 256,000 acre-feet, although this varies from 25,000 acre-feet to 635,000 acre-feet annually. The Humboldt River played an important part in the history of the American West during the early years of westward settlement. In 1928, Peter Skene Ogden led a party of Hudson’s Bay Company trappers south from Idaho, following the Humboldt to the present location of Winnemucca. Ogden trapped there briefly, returning to Utah for the winter. The following spring, he returned to follow the Humboldt to the marshes west beyond the Stillwater Range, where the Humboldt spreads and disappears into the desert sand. For ten years, British and American trappers worked the river, then called Mary’s River. By 1838, the beaver were largely trapped out, the market for beaver felt hats was waning, and the American west was about to change. Three years later, the first party of immigrants to California, on the advice of mountain men, followed the Humboldt west from near its source to the Humboldt Sink, then crossed the Forty-Mile Desert to reach the Carson River and the Sierra Nevada. In 1845, John C. Fremont began his explorations and publicized the desert country and the Humboldt Trail.

Abstract Interstate 80 between Elko and Carlin, Nevada, follows the valley of the Humboldt River. The Humboldt drains a 17,000 square mile basin along its 275 mile course, located entirely within the State of Nevada. While barely a trickle of water in late summer, spring floods may swell the river well over its banks. The average annual discharge is 256,000 acre-feet, although this varies from 25,000 acre-feet to 635,000 acre-feet annually. The Humboldt River played an important part in the history of the American West during the early years of westward settlement. In 1928, Peter Skene Ogden led a party of Hudson’s Bay Company trappers south from Idaho, following the Humboldt to the present location of Winnemucca. Ogden trapped there briefly, returning to Utah for the winter. The following spring, he returned to follow the Humboldt to the marshes west beyond the Stillwater Range, where the Humboldt spreads and disappears into the desert sand. For ten years, British and American trappers worked the river, then called Mary’s River. By 1838, the beaver were largely trapped out, the market for beaver felt hats was waning, and the American west was about to change. Three years later, the first party of immigrants to California, on the advice of mountain men, followed the Humboldt west from near its source to the Humboldt Sink, then crossed the Forty-Mile Desert to reach the Carson River and the Sierra Nevada. In 1845, John C. Fremont began his explorations and publicized the desert country and the Humboldt Trail.

The Late Ordovician fauna of the northern Hudson Bay Lowland, Manitoba, Canada, consisting of three stromatoporoid species (1 new), 41 coral (11 new and 2 new genera), 8 gastropod (1 new), 56 cephalopod (21 new and 1 new genus), and 1 graptolite species are described and in part illustrated. Brachiopods are listed only. This fauna was obtained from five formations consisting mostly of fossiliferous dolomitic limestone 300–400 feet thick. In ascending order these are: the Portage Chute and Surprise Creek formations of the Bad Cache Rapids Group; the Caution Creek and Chasm Creek formations of the Churchill River Group; and the Red Head Rapids Formation. The Bad Cache Rapids Group, which rests on peneplaned Precambrian, is correlated with the Red River Formation of southern Manitoba, the Churchill River Group with the Stony Mountain Formation, and the Red Head Rapids Formation questionably with the Stonewall Formation. The faunas indicate a close temporal relationship between the Bad Cache Rapids and Churchill River groups. The latter is considered Richmondian and in part Gamachian. A Late Ordovician age is thus also suggested for the Bad Cache Rapids Group and hence for the coeval Red River Formation.

Abstract Natural gas is produced in the states of New York and Pennsylvania from rocks of Pennsylvanian, Mississippian, Devonian, Silurian, Ordovician, and Ozarkian age. The limits of production are defined in Pennsylvania by the highly folded and faulted area in the central part of the state and in New York by the Adirondack Mountains and the valley of the Hudson. From a historic standpoint this region is very interesting since the first natural gas well was drilled and the first natural gas transmission line was laid in this area. The stratigraphy of the area covers almost the entire Paleozoic system of rocks. These rocks were deposited in the northern end of the Appalachian geosyncline. The most important gas-producing horizons represent shore-line deposits or the fine sand deposits of deltas or partly enclosed bays. There are more than 50 gas-producing horizons and more than 200 separate gas fields in the area. The dominating structural features are the Appalachian geosyncline and the system of folds and faults which originated during the Taconic and Appalachian revolutions. Gas occurrences in certain sandstones conform very closely to structural conditions but in general the character of the reservoir rocks is the most important factor in determining the accumulation of gas. The carbon ratio of the coals is an excellent index of the presence of oil or gas in the sandstones, but recent studies of certain of the more important reservoir rocks of the Chemung formation indicate that the permeability of the sandstone is of greater importance in limiting the area of oil production than the metamorphism of the rocks which was responsible for the progressive eastward devolatilization of the coals. The supply of gas in this part of Pennsylvania at present exceeds market demands, whereas for several years New York's production has been supplemented by large amounts of imported gas. The proved reserves of the Pennsylvania fields combined with the large reserves of neighboring states should be ample to supply the demands of this territory for many years.