997 resultados para Geology--United States--Maps


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The drumlin sediments at Chimney Bluffs, New York appear to represent a block-inmatrix style glacial melange. This melange comprises sand stringers, lenses and intraclasts juxtaposed in an apparently massive diamicton. Thin section examination of these glacigenic deposits has revealed microstructures indicative of autokinetic subglacial defonnation which are consistent with a deformable bed origin for the diamicton. These features include banding and. necking of matrix grains, oriented plasma fabrics and the formation of pressure shadows at the long axis ends of elongate clasts. Preservation of primary stratification within the sand intraclasts appears to suggest that these features were pre-existing up-ice deposits that were frozen, entrained, then deposited as part of a defonning till layer beneath an advancing ice sheet. Multi-directional micro-shearing within the sand blocks is thought to reflect the frozen nature of the sand units in such a high strain environment. It is also contended that dewatering of the sediment pile leading to the eventual immobilisation of the defonning till layer was responsible for opening sub-horizontal fissures within the diamicton. These features were subsequently infilled with mass flow poorly sorted sands and silts which were subjected to ductile defonnation during the waning stages of an actively deforming till layer. Microstructures indicative of the dewatering processes in the sand units include patches of fine-grained particles within a coarser-grained matrix and the presence of concentrated zones of translocated clays. However, these units were probably confined within an impermeable diamicton casing that prevented massive pore water influxes from the deforming till layer~ Hence, these microstructures probably reflect localised dewatering of the sand intraclasts. A layered subglacial shear zone model is proposed for the various features exhibited by the drumlin sediments. The complexity of these structures is explained in terms of ii superposing deformation styles in response to changing pore water pressures. Constructional glaciotectonics, as implied by the occurrence of sub-horizontal fissuring, is suggested as the mechanism for the stacking of the sand intraclast units within the diamicton. The usefulness of micromorphology in complimenting the traditional sedimentology of glacigenic deposits is emphasised by the current study. An otherwise massive diamicton was shown to contain microstructures indicative of the very high strain rates expected in a complexly deforming till layer. . It is quite obvious from this investigation that the classification of diamictons needs to be re-examined for evidence of microstructures that could lead to the re-interpretation of diamicton forming processes. RESUME Le pacquet de sediments drumlinaire de Chimney Bluffs, New York, represent un "bloc-en-matrice" genre de melange glaciale. Des structures microscopique comprennent l'evidence pour la defonnation intrinseque attribuee a l'origine lit non resistant du drumlin. PreselVation des structures primaires au coeur des blocs arenaces suggere que ceux sont des depots preexistant qui furent geles, entraines et par la suite sedimentes au milieu d'une couche de debris sous-glaciaires en voie de deformation. Des failles microscopiques a l'interieur des blocs arenaces appuient aussi l'idee d'un bloc cohesif (c'est-a-dire gele) au centre d'un till non resistant. Des implications significatives s'emergent de cette etude pour les conditions sous-glaciaire et les processus de la formation des drumlin.

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This layer is a georeferenced raster image of the historic paper map entitled: Map of the middle states of North America : shewing the position of the Geneseo country comprehending the counties of Ontario & Steuben as laid off in townships of six miles squar[e] each, Maverick, sculpt. It was printed by T. & J. Swords for Charles Williamson's Description of the settlement of the Genesee country, in the state of New-York, 1799. Scale [ca. 1:2,250,000]. Partial cadastral map showing large land purchases and township grants in New York State. Covers New York, Pennsylvania, Vermont, Massachusetts, Connecticut, New Jersey, Washington, D.C. and portions of Maryland, Delaware, and West Virginia. The image inside the map neatline is georeferenced to the surface of the earth and fit to the Universal Transverse Mercator (UTM) Zone 18N NAD83 projection. All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, index maps, legends, or other information associated with the principal map. This map shows features such as roads, drainage, major cities and towns, land purchases, township grants, state boundaries, and more. Includes key to "principal villages in Ontario & Steuben counties." This layer is part of a selection of digitally scanned and georeferenced historic maps from The Harvard Map Collection as part of the Imaging the Urban Environment project. Maps selected for this project represent major urban areas and cities of the world, at various time periods. These maps typically portray both natural and manmade features at a large scale. The selection represents a range of regions, originators, ground condition dates, scales, and purposes.

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This layer is a georeferenced raster image of the historic paper map entitled: Carte du Mexique : et des pays limitrophes situés au nord et à l'est, dressée d'après la grande cart de la Nouvelle Espagne de Mr. A. de Humbold et d'autres materiaux par J. B. Poirson ; gravé par Barriere et l'écriture par L Aubert. It was published by F. Schoell in 1811. Scale [ca. 1:8,000,000]. Map in French. Covers portion of North America, including the United States from the 42nd parallel south, Mexico, the Caribbean Islands east to Haiti, and portions of Guatamala, Belize, and Honduras. The image inside the map neatline is georeferenced to the surface of the earth and fit to the 'World Mercator' projection. All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, index maps, legends, or other information associated with the principal map. This map shows features such as drainage, cities, indian settlements and other human settlements, territorial boundaries, shoreline features, and more. Relief is shown by hachures. Includes historical notes. This layer is part of a selection of digitally scanned and georeferenced historic maps from the Harvard Map Collection and the Harvard University Library as part of the Open Collections Program at Harvard University project: Organizing Our World: Sponsored Exploration and Scientific Discovery in the Modern Age. Maps selected for the project correspond to various expeditions and represent a range of regions, originators, ground condition dates, scales, and purposes.

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Mode of access: Internet.

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Vol. [2] : maps.

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Numbering began with 15th Congress, as the publications of the earlier congresses were not assembled in book form.

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Accompanied by 6 maps (53 x 75 1/2 cm folded to 22 x 14 cm)

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"This atlas of the United States features maps reproduced from 'The United States gazetteer' and 'The new and universal gazetteer' published respectively in 1795 and 1800 by Joseph Scott of Philadelphia."