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The USGS provides unbiased, objective, and impartial scientific information upon which our audiences, including resource managers, planners, and other entities, rely.
Browse more than 65,000 articles authored by our scientists over the past 100+ year history of the USGS and refine search by topic, location, year, and advanced search.
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Ejecta from large craters on the Moon: Comments on the geometric model of McGetchin et al.
Amendments to a quantitative scheme developed by T.R. McGetchin et al. (1973) for predicting the distribution of ejecta from lunar basins yield substantially thicker estimates of ejecta, deposited at the basin rim-crest and at varying ranges byond, than does the original model. Estimates of the total volume of material ejected from a basin, illustrated by Imbrium, also are much greater. Because ma
Authors
R.J. Pike
Electrophoresis as a management tool
The theme of this 1974 Northeast Fish and Wildlife Conference is 'A New Era'. Indeed, it is a new era for improved techniques to assist in management of our fish and wildlife resources for the maximum benefit of all. In some cases, the new techniques are primarily used in research.on fish and wildlife, and the results from the research are used to aid management and enforcement agencies in the d
Authors
R.P. Morgan, J.A. Chapman, L.A. Noe, C. J. Henny
Enzyme changes in mallard ducks fed iron or lead shot
No abstract available.
Authors
R.S. Rozman, L. N. Locke, S.F. McClure
Episodic Cenozoic volcanism and tectonism in the Andes of Peru
Radiometric and geologic information indicate a complex history of Cenozoic volcanism and tectonism in the central Andes. K-Ar ages on silicic pyroclastic rocks demonstrate major volcanic activity in central and southern Peru, northern Chile, and adjacent areas during the Early and Middle Miocene, and provide additional evidence for volcanism during the Late Eocene. A provisional outline of tecton
Authors
D. C. Noble, E. H. McKee, E. Farrar, U. Petersen
Epitheliocystis and lymphocystis: a comparison of hypertrophied fish cells
No abstract available.
Authors
K. Wolf
Erosion by catastrophic floods on Mars and Earth
The large Martian channels, especially Kasei, Ares, Tiu, Simud, and Mangala Valles, show morphologic features strikingly similar to those of the Channeled Scabland of eastern Washington, produced by the catastrophic breakout floods of Pleistocene Lake Missoula. Features in the overall pattern include the great size, regional anastomosis, and low sinuosity of the channels. Erosional features are st
Authors
V.R. Baker, D. J. Milton
Estimating survival rates from banding of adult and juvenile birds
The restrictive assumptions required by most available methods for estimating survival probabilities render them unsuitable for analyzing real banding data. A model is proposed which allows survival rates and recovery rates to vary with the calendar year, and also allows juveniles to have rates different from adults. In addition to survival rates and recovery rates, the differential vulnerability
Authors
D. H. Johnson
Everglade kites feed on nonsnail prey
The Everglade Kite (Rostrhamus sociabilis plumbeus) of Florida has been called snail hawk or snail kite because it was thought to feed exclusively on the soft parts of the freshwater apple snail (Pomacea paludosa) (Nicholson 1926, Howell 1932, Bent 1937, Snyder and Snyder 1969). Furthermore, the other three subspecies of this wide-ranging Neotropical raptor (Friedmann 1950) are known to feed only
Authors
P.W. Sykes, H.W. Kale
Feeding ecology of pintail hens during reproduction
Food supply has been acknowledged as one of eight major external factors regulating the sexual cycles of birds (Marshall 1961). Several hypotheses have been advanced to explain the role of food supply as an ultimate factor regulating breeding (Marshall 1951; Lack 1954, 1968; Wynne-Edwards 1962; and others). Another potential influence of food is its being a proximate stimulus to breeding. When cer
Authors
G.L. Krapu
Fish age as related to susceptibility to Myxosoma cerebralis, cause of whirling disease
No abstract available.
Authors
G. L. Hoffman, C.J. Byrne