| Abstract: | Most sedimentary structures represented in sand bodies of the Rio Orinoco are tabular-planar cross-strata which, together with some wedge-planar cross-strata, are the products of sand-wave deposition. Locally, in areas of river meander where point bars characteristically form, trough structures forming festoon patterns are numerous. At a few localities, sets of nearly horizontal strata occur between tabular-planar sets and are interpreted to be the deposits of very fast currents of the upper flow regime; elsewhere, uncommon lenses and beds of silt, clay, or organic matter consisting of leaves and twigs, seem to be the result of quiet-water settling through gravity.
By far the most common grain size represented in the tabular-planar and wedge-planar cross-strata of the sandwave deposits is medium sand (? - ? millimeter) as determined by screen analyses. Many samples, however, also contain moderate quantities of coarse or very coarse sand. Eolian dunes on top of the sand-wave deposits are dominantly fine grained. The river channel sands were determined to be largely moderately well sorted, although in some places they were mostly well sorted, and in others, mostly moderately sorted. |
| Genre: | USGS Numbered Series |
| ProdID: | 2259 |
| Citation Author: | McKee, Edwin Dinwiddie |
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| Citation Language: | ENGLISH |
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| Citation Phsyical Description: | viii, 23 p. :ill. (some col.) ;28 cm. |
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| Citation Publisher: | U.S. G.P.O. ;
For sale by the Books and Open-File Reports Section, U.S. Geological Survey, |
| Citation Series: | Water Supply Paper |
| Citation Series Code: | WSP |
| Citation Series Number: | 2326-B |
| Citation Search Results Text: | Sedimentary structures and textures of Rio Orinoco channel sands, Venezuela and Colombia; 1989; WSP; 2326-B; McKee, Edwin Dinwiddie |
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| Citation Year: | 1989 |
| Type: | citation/reference |
| Text: | Sedimentary structures and textures of Rio Orinoco channel sands, Venezuela and Colombia; 1989; WSP; 2326-B; McKee, Edwin Dinwiddie |
| URL (THUMBNAIL): | http://pubs.usgs.gov/wsp/2326b/report-thumb.jpg |
| URL (DOCUMENT): | http://pubs.usgs.gov/wsp/2326b/report.pdf |
| Date Other: | Sat, 1 Jan 1994 00:00 -0600 |
| Publisher: | U.S. G.P.O. ;
For sale by the Books and Open-File Reports Section, U.S. Geological Survey, |
