| Abstract: | The Umpqua Formation (as herein restricted) consists of as much as 10,000 ft of mudstone, sandstone, and conglomerate of nonmarine to deep marine origin. A basaltic basement that underlies the sedimentary rocks in most of the area and was formerly included in the Umpqua is herein considered a separate unit and assigned to the Siletz River Volcanics. A proposal to subdivide the Umpqua into three unconformity-bounded formations in the area west of Roseburg, Oregon, is not recognized in this report because of questionable correlations and limited extent of some units. The Tyee Formation, which conformably overlies the Umpqua, is a predominantly sandstone unit about 6,000 ft thick, deposited in environments ranging from shallow marine and nonmarine deltaic on the south, to slope and deep marine basinal to the north. Deposition across the Umpqua-Tyee boundary contact represents a change in tectonic setting. Refs. |
| Genre: | Article |
| ProdID: | 70012742 |
| Citation Author: | Molenaar, C. M. |
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| Citation End Page: | 1229 |
| Citation Issue: | 8 |
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| Citation Language: | English |
| Citation Larger Work Title: | American Association of Petroleum Geologists Bulletin |
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| Citation Number Of Pages: | 13 |
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| Citation Search Results Text: | DEPOSITIONAL RELATIONS OF UMPQUA AND TYEE FORMATIONS (EOCENE), SOUTHWESTERN OREGON.; 1985; Article; Journal; American Association of Petroleum Geologists Bulletin; Molenaar, C. M. |
| Citation Start Page: | 1217 |
| Citation Volume: | 69 |
| Citation Year: | 1985 |
| Type: | citation/reference |
| Text: | DEPOSITIONAL RELATIONS OF UMPQUA AND TYEE FORMATIONS (EOCENE), SOUTHWESTERN OREGON.; 1985; Article; Journal; American Association of Petroleum Geologists Bulletin; Molenaar, C. M. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Tue, 1 Jan 1985 00:00 -0600 |
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