Proterozoic metamorphism and uplift history of the north-central Laramie Mountains, Wyoming, USA

2001 ◽  
Vol 17 (3) ◽  
pp. 243-258 ◽  
Author(s):  
PATEL ◽  
FROST ◽  
CHAMBERLAIN ◽  
SNYDER†
Keyword(s):  
North Central ◽  
The North ◽  
History Of ◽  
Uplift History ◽  
Laramie Mountains

Within-field Pathogenic Diversity of Phytophthora sojae in Commercial Soybean Fields in Iowa

2009 ◽  
Vol 10 (1) ◽  
pp. 8 ◽  
Author(s):  
Alison E. Robertson ◽  
Silvia R. Cianzio ◽  
Sarah M. Cerra ◽  
Richard O. Pope
Keyword(s):  
The United States ◽  
Phytophthora Sojae ◽  
Soil Samples ◽  
Soybean Plant ◽  
North Central Region ◽  
North Central ◽  
The North ◽  
History Of ◽  
The Many ◽  
Pathogenic Diversity

Phytophthora root and stem rot (PRR), caused by the oomycete Phytophthora sojae, is an economically important soybean disease in the north central region of the United States, including Iowa. Previous surveys of the pathogenic diversity of P. sojae in Iowa did not investigate whether multiple pathotypes of the pathogen existed in individual fields. Considering the many pathotypes of P. sojae that have been reported in Iowa, we hypothesized multiple pathotypes could exist within single fields. In the research reported herein, several soil samples were collected systematically from each of two commercial fields with a history of PRR in Iowa, and each soil sample was baited separately for isolates of P. sojae. Numerous pathotypes of P. sojae were detected from both fields. As many as four pathotypes were detected in some soil samples (each consisting of six to eight soil cores), which suggests that a single soybean plant could be subjected to infection by more than one pathotype. This possibility presents important implications in breeding resistant cultivars and in the management of PRR. Accepted for publication 14 July 2009. Published 8 September 2009.

Exhumational history of the north central Pamir

Tectonics ◽  
2010 ◽  
Vol 29 (5) ◽  
pp. n/a-n/a ◽  
Author(s):  
William H. Amidon ◽  
Scott A. Hynek
Keyword(s):  
North Central ◽  
The North ◽  
History Of

Sedimentology and stratigraphy of the Cretaceous Virginian Ridge Formation, Methow Basin, Washington

1985 ◽  
Vol 22 (9) ◽  
pp. 1274-1285 ◽  
Author(s):  
James H. Trexler Jr.
Keyword(s):  
Upper Cretaceous ◽  
Western North America ◽  
The West ◽  
Detailed Model ◽  
North Central ◽  
North American Cordillera ◽  
The North ◽  
History Of ◽  
Tectonic Settings ◽  
Overlying Strata

The Cretaceous Methow Basin of north-central Washington is the southernmost of a series of Mesozoic successor basins in the Cordillera of western North America. The Albian–Campanian(?) Virginian Ridge Formation comprises three members, newly defined here, that gradationally interfinger with each other and grade laterally and upward into overlying strata. Detailed stratigraphic analysts of the Virginian Ridge Formation and of the intimately related parts of the Winthrop and Midnight Peak formations indicates that these units represent complexly interfingering facies derived from a variety of sources, both to the west and to the east of the basin and locally within the system. This study suggests a detailed model for the history of the Upper Cretaceous Methow Basin: generation of a restricted basin with a stable, roughly north–south-trending axis, filled by a stable, east-derived fluvial and deltaic system (Winthrop Formation) interfingering with a laterally amalgamated, west-derived northward and eastward transgressive fan-delta system (Virginian Ridge Formation). The sequence grades upward into, and finally is overwhelmed by, locally derived volcanics of the Midnight Peak Formation. Similar, and in part coeval, successor basin sequences throughout the North American Cordillera may have been generated in response to similar tectonic settings.

scholarly journals Vegetational History of Yellowstone Park as Determined by Pollen Analysis

1978 ◽  
Vol 2 ◽  
pp. 87-91
Author(s):  
George Frison ◽  
Jane Beiswenger
Keyword(s):  
Sediment Cores ◽  
Lake Basin ◽  
Large Lake ◽  
Yellowstone Lake ◽  
North Central ◽  
University Of Utah ◽  
The North ◽  
History Of ◽  
Park Area ◽  
The University

The purpose of this project was to interpret the vegetational history of the Yellowstone Park area by the analysis of pollen contained in sediment cores from four locations in Yellowstone Lake. The cores, collected by Dr. Robert Smith of the University of Utah, were from the north central portion, the west thumb area, the south arm and the southeast arm of the lake. The cores were to be compared to determine pollen variations within the lake. Differences between a small pond and a large lake basin in reflecting climatic change were to be studied by comparing the results with pollen counts from Fifteen Foot Lagoon (Baker, 1976).

On the land mammals of the Queen Charlotte Islands, British Columbia, by John Henry Keen, with a catalogue of specimens

2017 ◽  
Vol 44 (2) ◽  
pp. 259-274 ◽  
Author(s):  
S. G. Sealy
Keyword(s):  
British Columbia ◽  
Natural History ◽  
The United States ◽  
Haida Gwaii ◽  
North Central ◽  
Queen Charlotte Islands ◽  
The North ◽  
Annotated List ◽  
History Of ◽  
Evolution Of Mammals

From 1890 to 1899, the Reverend John Henry Keen collected plants and animals in the vicinity of the Anglican mission at Massett, on the north-central coast of the Queen Charlotte Islands (Haida Gwaii), British Columbia, Canada. Keen's prodigious collecting efforts resulted in the first detailed information on the natural history of that region, particularly of the beetle fauna. Keen also observed and collected mammals, depositing specimens in museums in Canada, England and the United States, for which a catalogue is given. Several mammal specimens provided the basis for new distributional records and nine new taxa, two of which were named for Keen. In 1897, Keen prepared an annotated list of ten taxa of land mammals of the Queen Charlotte Islands, including the first observations of natural history for some of the species. Particularly important were the insightful questions Keen raised about the evolution of mammals isolated on the Islands, especially why certain species, abundant on the mainland, were absent.

An updated and refined Holocene uplift history of southern Tenerife (Canary Islands) and the possible consequences for future volcanic activity

2015 ◽  
Vol 152 (6) ◽  
pp. 1137-1144
Author(s):  
E. BUCHNER ◽  
J. KRÖCHERT ◽  
M. SCHMIEDER
Keyword(s):  
Canary Islands ◽  
Volcanic Activity ◽  
The South ◽  
The Past ◽  
The North ◽  
Stable Conditions ◽  
Tenerife Island ◽  
History Of ◽  
Uplift History

AbstractVarious uplift markers suggest asymmetrical uplift of Tenerife Island, with stable conditions in the north but significant uplift of up to 45 m in the south over the past ~42 ka. Fossil shells in beach deposits uplifted by 7.5–9 m were 14C-dated at a Holocene age of 2460±35 bp (1σ). This confirms earlier results and documents very young, and probably still ongoing, uplift of southern Tenerife potentially caused by ascending magma. This underlines that southern Tenerife is probably undergoing a further cycle of volcanic activity that started ~95 ka ago.

Comparative Precambrian geochronology of the North American, European, and Siberian Shields

1969 ◽  
Vol 6 (3) ◽  
pp. 357-365 ◽  
Author(s):  
R. A. Burwash
Keyword(s):  
Statistical Treatment ◽  
Geologic History ◽  
Northern Asia ◽  
North Central ◽  
Mean Values ◽  
The North ◽  
Central United States ◽  
History Of ◽  
The Difference ◽  
The Baltic

A comparison of average values of U–Pb, Rb–Sr, and K–Ar isotopic dates from Precambrian shields in North America, Europe, and northern Asia suggests three major orogenies common to all areas. U–Pb and Rb–Sr age determinations, qualified by the more numerous K–Ar data, suggest mean values of 2600 ± 100 m.y., 1800 ± 100 m.y. and 1000 ± 100 m.y. An earlier event at 3300 to 3500 m.y. is locally recognizable in the Baltic Shield, the Ukrainian Shield, and the north-central United States. Anorogenic igneous events intermediate between the major orogenies are indicated in the Canadian, Ukrainian, and Aldan Shields, but these are as yet unmatched outside their own restricted settings.Isotopic dates are divided into two categores: anorogenic and orogenic. Within a specified orogeny, dates are further divided into precrystalline, syncrystalline, and postcrystalline. Regional correlations ideally should be based only on syncrystalline dates, recording times of final crystallization, unmodified by subsequent processes except initial cooling. Depth of crystallization and rate of uplift determine the difference between true and apparent time of crystallization. Precrystalline dates (survival values) and postcrystalline (rejuvenated or overprinted) dates should be excluded from the designated span of major orogenies.Rigorous statistical treatment of isotopic dates seems unwarranted on the basis of uncertainties in the geologic history of most rock bodies. Histograms may aid in the identification of anorogenic and precrystalline dates.

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