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Research about Canada, United States

Source-linked reports with geographic coverage including Canada, United States.

At least 1,297 records · Page 72Linked to original sources
USGS1968

Biostratigraphic classification of the marine Triassic in North America

Ammonoid faunas representative of every major part of Triassic time occur at one place or another in the marine Triassic strata of western and arctic North America. Though some intracontinental provincialism is evident, particularly among Lower and Middle Triassic ammonoid faunas, various local sections where parts of the faunal sequence are preserved—sections in southeastern Idaho, western Nevada, northern California, northeastern Oregon, northeastern British Columbia, southwestern British Columbia, southeastern and southern Alaska, and the Arctic Islands of Canada—can be pieced together in overlapping fashion into a unified sequential framework of biostratigraphic units presented in an annotated zonal chart. At least 35 zonal units of demonstrably different age are now recognized; these units are apportioned among the Griesbachian, Dienerian, Smithian, and Spathian Stages of the Lower Triassic; the Anisian and Ladinian Stages of the Middle Triassic; and the Karnian, Norian and Rhaetian Stages of the Upper Triassic. This zonation based on North American ammonoid faunas for the first time provides an objective and reasonably detailed standard of reference for expressing the age and correlation of the marine Triassic rocks of Canada and the United States.

Alaska, Arctic, British Columbia, California, Idah↗
USGS1968

Aerial estimation of the size of gull breeding colonies

Counts on photographs and visual estimates of the numbers of territorial gulls are usually reliable indicators of the number of gull nests, but single visual estimates are not adequate to measure the number of nests in individual colonies. To properly interpret gull counts requires that several islands with known numbers of nests be photographed to establish the ratio of gulls to nests applicable for a given local census. Visual estimates are adequate to determine total breeding gull numbers by regions. Neither visual estimates nor photography will reliably detect annual changes of less than about 25 percent.

Journal of Wildlife Management↗
USGS1967

Growth of lake trout in Lake Superior before the maximum abundance of sea lampreys

The growth in length of lake trout (Salvelinus namaycush) from the inshore water of Lake Superior in 1953 increased with age from the 3rd to 9th year, and was nearly constant from the 9th to the 12th year. Growth was greatest in the 1st year (4.0 inches) and least in the 2nd and 3rd years (2.3 inches). Between the 4th and 9th years the increments increased from 2.6 to 3.5 inches. Growth was calculated from a curvilinear body‐scale relation. Intraseasonal growth in length extended from late April until well after October; most growth was in late summer and fall. The younger fish started growth earlier, and some mature fish did not increase in length until after the October spawning. Lake trout reached the minimum legal weight (1.5 pounds) in the 7th year of life and the average size taken in the commercial fishery (about 3 pounds) in the 8th year. The annual increase in weight in the 8th year of life was over 64%. Fish used in this study grew more slowly than those from Lakes Michigan and Huron taken during the period when sea lamprey abundance was increasing, but at about the same rate as lake trout of Lake Michigan before the sea lamprey appeared.

Lake Superior↗
USGS1967

Geologic framework and petroleum potential of the Atlantic Coastal Plain and continental shelf, with a section on stratigraphy

The Atlantic Coastal Plain and Continental Shelf of North America is represented by a belt of Mesozoic and Cenozoic rocks, 150 to 300 miles wide and 2,400 miles long, extending from southern Florida to the Grand Banks of Newfoundland. This belt of Mesozoic and Cenozoic rocks encompasses an area of about 400,000 to 450,000 square miles, more than three-fourths of which is covered by the Atlantic Ocean. The volume of Mesozoic and Cenozoic rocks beneath the Atlantic Coastal Plain and Continental Shelf exceeds 450,000 cubic miles, perhaps by a considerable amount. More than one-half of this is seaward far enough to contain marine source rocks in sufficient proportion to attract exploration for oil. A larger fraction, perhaps three-quarters of the volume, may be of interest in exploration for gas. The Coastal Plain consists of land between the crystalline piedmont of the Appalachian System and mean low-tide from southern Florida to the tip of Long Island plus a few small offshore islands and the Cape Cod Peninsula. This is an area of more than 100,000 square miles. The Continental Shelf extends from mean law-tide to the break marking the beginning of the continental rise, which is somewhat less than 600 feet in depth at most places. It is a gently sloping platform, about 350,000 square miles in area, that widens from less than 3 miles off southern Florida to about 285 miles off Newfoundland. The Blake Plateau occupies an area of about 70,000 square miles between the 500 and 5,000-foot bottom contours from the Cape Hatteras vicinity to the northernmost bank of the Bahamas. It has a gentle slope with only minor irregularities and scattered patches of Recent sediments. Both gravity and magnetic anomalies along the Atlantic Coast reflect primarily compositional differences at considerable depths in the earth's crust, but are related to some extent to the structure and composition of the Coastal Plain sedimentary rocks and shallow basement. Four alternating belts of predominantly positive and predominantly negative Bouguer gravity anomalies extend diagonally across the region from southwest to northeast. These correspond roughly with the continental rise and slope, the Continental Shelf and Coastal Plain, the Appalachian Mountain System front, and the Piedmont Plateau-Blue Ridge-Appalachian Basin region.

Atlantic Coastal Plain↗
USGS1967

Succession of rugose coral faunas in the Lower and Middle Devonian of eastern North America

Rocks of Early Devonian age are widely but sporadically distributed in the eastern half of North America and coral studies are based on a very incomplete record. Middle Devonian rocks are thicker and cover a greater area. Both Early and Middle Devonian corals are more similar to western European species than they are to presumably contemporary forms from western North America, although some of the eastern faunas contain a significant portion of endemic genera. The general outline of an eastern province was inherited from the Silurian, but disappeared by Late Devonian time when the worldwide Frasnian fauna invaded the area. A reef fauna of middle Helderberg age is known from the northeast part of the province and is composed of both endemic and widespread genera. Approximately contemporaneous off-reef deposits have few species, but these are common in argillaceous rocks of a somewhat larger area. Rocks of middle Onesquethaw (Schoharie) age, although thin and discintinuous, include the largest and most widespread Early-Devonian coral fauna. Endemic genera are numerous but other elements are widespread and some species are apparently ancestral to species in the succeeding Onondaga fauna. The late Onesquethaw (Onondaga) faunas are the largest and most widely distributed of all those under review. Succeeding faunas of the Cazenovia, Tioughnioga and Taghanic Stage (Hamilton-Tully sequence) are less widespread and are clearly derivatives of the late Onesquethaw fauna. The Taghanic fauna is the latest Middle Devonian rugose coral fauna in the area

Indiana, Kentucky, Maine, Maryland, New Brunswick,↗
USGS1967

Devonian of the Appalachian Basin, United States

Although Devonian rocks in the Appalachians have been studied for more than 150 years, they are poorly known in most of the area. The nearly complete Devonian sequence in New York has been established as the North American standard of reference. The structural belt that includes unmetamorphosed Devonian geosynclinal strata is bonded on the southeast and east by metamorphic and igneous rocks of the Blue Ridge and Piedmont provinces. Some meta-sedimentary and igneous rocks of the Piedmont may be Devonian, but the only rocks known to be of this age southeast of the structural belt are mudstones and siltstones in the subsurface of northwest Florida and adjacent Georgia. The three oldest stages of the Devonian in the Appalachian area — Helderberg, Deerpark, and Onesquethaw— consist (in ascending order) of carbonate, clastic, and carbonate rocks across an increasingly broad area. The rock units are thin, and facies relations are complex. Most units appear to have accumulated on a relatively stable base in medium- to high-energy environments. Significant subsidence began in Onesquethaw time and continued into the Carboniferous. Concurrently uplifted source areas to the east shed vast amounts of detritus, most of which was trapped in the trough. Middle and Upper Devonian strata are dominantly shallow-marine, fine-grained clastic rocks. These reach a maximum thickness of over 11,000 feet in eastern Pennsylvania. Middle Devonian terrestrial rocks occur locally on the east side of the structural belt. By the close of the Devonian they had spread widely over the northern half of the geosyncline. On the craton, the Middle and Upper Devonian rocks are limestones and shales, but units are thin and discontinuous except for black shale, which, over broad areas, is the latest Devonian deposit. Deposition of this shale persisted into post-Devonian times.

Alabama, Delaware , Georgia, Indiana, Kentucky, Ma↗
USGS1959

Waterfowl sickness diagnoses in Minnesota, North Dakota, and Manitoba

This paper reports the results of an attempt to determine whether botulinus toxin or some other factor was responsible for avian sickness on water bodies in Minnesota, North and South Dakota, and at Whitewater Lake, Boissevain, Manitoba, in the summer of 1953.

Manitoba, Minnesota, North Dakota↗
USGS1958

Recent underwater surveys using low-frequency sound to locate shallow bedrock

Underwater investigations at Lake Mead, Chicago, Passamaquoddy Bay, and on Long Island established the characteristics of sound waves that can be used in shallow geophysical exploration by the sonar method. At Lake Mead the sediments were for the most part clay of high water content which was easily penetrated by low-power sound at a frequency of 14.2 kilocycles. The greatest depth of penetration was 140 feet. Sound having frequencies of 50 and 80 kilocycles did not penetrate. At Chicago, sound at a frequecy of 11 kilocycles and an output power of 800 watts gave a satisfactory delineation of bedrock beneath Lake Michigan. The maximum distance to bedrock was about 135 feet. At Passamaquoddy Bay a sound frequency of 6 kilocycles and about 700 watts of output power gave much better delineation of bedrock. A frequency of 6 kilocycles at the lower output power was much better than 11 kilocycles at higher power. About 250 feet of penetration was attained. Pulsed power was used in each of these investigations. The pulse lengths were long—about 14–25 milliseconds. Bedrock was mapped at Lake Mead, Chicago, and Passamaquoddy Bay. The methods of ordinary hydrographic surveying were used for horizontal and vertical positioning. For horizontal positions the ordinary three-point sextant-fix method was used. For vertical positioning, recording gages suitably placed and supplemented by staff gages were used. All data were tied into the third-order control net of the U. S. Coast and Geodetic Survey. In connection with a study for a proposed Midwestern waterway, the technical problem was reviewed and the techniques considerably improved. New equipment was built and evaluated on Long Island Sound. It operated with pulsed power at a frequency of 6 kilocycles, and pulse length was controlled and variable from 1 to 9 milliseconds. Output acoustic power was about 2500 watts. With the transducer in ordinary operating positions as much as 400 feet of sediment was penetrated. With the transducer placed directly on the bottom of the water in Huntington Bay about 750 feet of penetration was attained. Several innovations in sonar techniques, which are desirable for sediment exploration, and which give much more detailed information than the earlier equipment are described. The techniques required for stratigraphic interpretation of the sound records are described briefly. A method for the determination of sound velocities is discussed. Multiple echoes and other effects complicate the interpretation of records and are explained. The problems of geological control encountered also are mentioned.

Illinois, Maine, Nevada, New Brunswick, New York↗
USGS1957

The nutrition of salmonid fishes. I. Chemical and histological studies of wild and domestic fish

Salmonids reared under artificial conditions show marked consistent differences in body composition in comparison with wild salmonids. Protein and mineral levels are lower and lipid values are higher in hatchery fish than in wild fish. As the period of artificial rearing is increased, these differences become more extreme. In hatchery fish, there is generally more microscopically visible fat in the liver and viscera than in these organs in wild fish although extremes are seen in both groups. In young hatchery fish and in wild fish, there is no correlation between fat deposition in the liver and in the pancreas, but in older hatchery fish, both of these organs are fatty and there is a simultaneous increase in total body lipid. In wild fish, ceroid deposition is greater, suggesting that the fatty acids are more highly unsaturated. There is little difference in disease incidence between the two groups, but parasitism is more pronounced in wild fish. The significant variables between wild and artificially produced fish appear to be limited to diet and environment. From the factors discussed above, diet alone is probably the most important single factor in producing the changes observed in body composition.

Alaska, British Columbia, California, Oregon, Wash↗
USGS1957

New host and locality record for Triaenophorus crassus forel (Cestoda: pseudophyllidea)

The adult form of Triaenophorus crassus Forel, 1868 (= T. robustus Olsson, 1893; = T. tricuspidatus morpha megadentatus Wardle, 1932) occurs as an intestinal parasite in the pike, Esox lucius L., a holarctic species of wide distribution. Preliminary life-history stages include procercoid development in copepods of the genus Cyclops followed by plerocercoid development in the musculature of a variety of coregonid and salmonid fishes. The unsightly appearance of even moderate plerocercoid infections is often sufficient to render fish unacceptable for human consumption. In the prairie provinces of Canada the incidence and intensity of T. crassus infections in the commercially important whitefishes constitute a serious economic problem.

Alaska, British Columbia, Northwest Territories↗