Our studies and those of our colleagues in Idaho indicate that the western Snake River Basin is a major geothermal province, similar in some ways to the Imperial Valley Geothermal Province. Deep drilling should encounter high temperature fluids in permeable rocks below 2 km and at shallower depths where permeability...
Let us travel the 65-mile length of the Columbia River Gorge for a closer look at the rock formations and geology of the area. We will supplement our observations with information from the literature on the geology of the Gorge and try to put together a picture of how the...
Periodic violent eruptions from many different centers during Cenozoic time deposited vast quantities of pyroclastic material as ash-flow tuffs over most of Oregon, although the Coast Ranges and isolated patches elsewhere in the state appear to have been spared these recurring inundations. Eruptions occurred at different times throughout the Cenozoic,...
Wright's Point, a 250-foot-high, sinuous, flat-topped ridge, projects eastward into Harney Basin, Harney County, Oregon. This 6-mile-long feature ranges from 200 to 600 yards wide and merges with a broad mesa at its western end. The nearest topographic highs are Dog Mountain, 2 miles southwest, and foothills of the Blue...
One of the most beautiful and geologically interesting parts of the Oregon coast is in the vicinity of Cape Arago near Charleston, 10 miles west of Coos Bay. Three very fine state parks have been developed here. They are (from north to south): Sunset Bay, Shore Acres, and Cape Arago...
(1) Field mapping and biostratigraphic data indicate that the Yamhill Formation overlies and is younger than the Tyee Formation; interfingering of the two formations is not indicated. (2) Stewart's correlation of the Yamhill Formation with the Sacchi Beach member of the Tyee was based on incomplete knowledge of the range...
This report summarizes results of geologic mapping in the South Umpqua Falls region of the Western Cascade Range in Douglas County, southwestern Oregon (plate 1). Rocks of the Western Cascades range in age from late Eocene to late Miocene and consist of deformed and partially altered flows, pyroclastic rocks, and...
The plate tectonic history of Oregon is but one piece of a worldwide jigsaw puzzle encompassing much of geologic time. With the splitting of Pangaea in Mesozoic times, Oregon has occupied the leading edge of the North American Plate as it has impinged upon the ancestral oceanic East Pacific Plate....
The following outline of events in the rise and fall of gold mining in southwestern
Oregon is here recorded - almost as an obituary - so that Oregonians may not entirely forget how important this industry was in building up this part of the state.
This report presents a summary of the principal geologic and physiographic features of the upper part of the Snake River Canyon between Oregon and Idaho. The area discussed extends from Farewell Bend near Huntington, Oregon downriver to Granite Creek 6 miles below Hells Canyon Dam, a distance of 94 miles....
The geology of Oregon has become a jigsaw puzzle of moving parts set on a foundation of changing conditions as the crust and mantle undergo successively different manners of deformation through time. As more megahypotheses arise from increasingly sophisticated views of plate tectonics and from more detailed analyses of synoptic...
The purpose of this paper is to give a brief description of the volcano, and to report progress in the detailed mapping and petrologic study of its caldera. The increasing use of the Paulina and East Lake areas for recreation and nature study, and widespread interest in the geology aroused...
This field trip consists of two geologic tours. On Tour 1, the Tertiary sedimentary rocks exposed along the Yaquina River between Newport and Toledo, Oregon, will be examined. This tour will start at the mouth of Yaquina Bay where Miocene sedimentary rocks are exposed and will proceed generally eastward and...
Gravity measurement program in Oregon / John V. Thiruvathukal and Joseph W. Berg, Jr. -- The principle of discovery and the problems arising therefrom / Raymond B. Holbrook.
The stacks off the southern Oregon coast have been studied very little because of difficulties of access (see, for example, Weissenborn and Snavely, 1968). Work described herein was helicopter-supported; skillful piloting by Earl Lady permitted landings on or close approaches to many stacks. To help delineate the structure, field work...
A free-air gravity anomaly map of the area between 10°-17°N and
90°-101°W shows distinctive positive and negative anomalies which
parallel the Tehuatepec Ridge. The positive anomaly approximately
overlies the topographic expression of the ridge. On the wide continental
shelf southeast of the Gulf of Tehuantepec a positive gravity
anomaly with...
Gravity and seismic data obtained by the geophysical group at
Oregon State University on the R/V YAQUINA during 1969, 1971, and
1973 plus other available data over the area just west of Nicaragua
and Costa Rica indicate the tectonic complexity of the region. Gravity
measurements show negative free-air anomalies over...
The U.S. Forest Service has published the final version of regulations on the surface use of National Forest lands under the amended mining laws of 1872. These regulations became effective September 1, 1974. Although the Mining Law of 1872 is still largely intact, the new regulations place some requirements in...
"It is the purpose of this paper, through a brief review of the history of Astoria, to construct a framework of the physical history of the city, to place each published geologist in his correct historical setting within the city, and to reestablish his locales so as to be presently...
When you drive through the Madras region on U.S. Highway 97, you see a gently rolling plain dotted with low hills and flat-topped buttes. Since the plain appears to extend westward uninterruptedly to the foothills of the Cascade Range, little would you imagine that between you and the mountains lurk...
Average annual losses caused by geologic hazards in Oregon are difficult to determine, owing to incomplete and scattered data. Preliminary considerations, however, indicate that losses to landslides may total between $4 million and $40 million per year. As many as nine persons have been killed by one landslide in Oregon...
The United States has enormous deposits of oil shale which, if developed, could provide energy resources for centuries. Because of the vast size of these deposits, they are currently receiving a great deal of attention. This issue of The ORE BIN is devoted to a discussion of oil shale --...
The purpose of this study of the Lyons flora is to determine the age and paleoecology of the flora through the examination and identification of the fossil plant species of the flora. The plant fossils comprising the Lyons flora were collected from a locality in the upper Thomas Creek area,...
The purpose of this paper is to give some account of the fossil shark faunas of Oregon. This has been, at best, only introductory to the more than 5,000 specimens now being studied by the author. Many of the genera are listed in Figure 2, but species determinations have not...