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U.S. Geological Survey

Publications and source records attributed to U.S. Geological Survey.

At least 163 records · Page 9Linked to original sources
USGS1997

Mud fossils

At the close of the 18th century, the haze of fantasy and mysticism that tended to obscure the true nature of the Earth was being swept away. Careful studies by scientists showed that rocks had diverse origins. Some rock layers, containing clearly identifiable fossil remains of fish and other forms of aquatic animal and plant life, originally formed in the ocean. Other layers, consisting of sand grains winnowed clean by the pounding surf, obviously formed as beach deposits that marked the shorelines of ancient seas.

General Information Product↗
USGS1997

Geologic age: using radioactive decay to determine geologic age

At the close of the 18th century, the haze of fantasy and mysticism that tended to obscure the true nature of the Earth was being swept away. Careful studies by scientists showed that rocks had diverse origins. Some rock layers, containing clearly identifiable fossil remains of fish and other forms of aquatic animal and plant life, originally formed in the ocean. Other layers, consisting of sand grains winnowed clean by the pounding surf, obviously formed as beach deposits that marked the shorelines of ancient seas. Certain layers are in the form of sand bars and gravel banks -- rock debris spread over the land by streams. Some rocks were once lava flows or beds of cinders and ash thrown out of ancient volcanoes; others are portions of large masses of once-molten rock that cooled very slowly far beneath the Earth's surface. Other rocks were so transformed by heat and pressure during the heaving and buckling of the Earth's crust in periods of mountain building that their original features were obliterated.

General Information Product↗
USGS1997

Activities Related to American Indians and Alaska Natives; Fiscal Year 1997

Introduction This report primarily describes activities during Federal fiscal year (FY) 1997. During FY 1997, the USGS engaged in cooperative research projects, data collection, informal outreach, and work done under Memoranda of Understanding that related to American Indians or Alaska Natives. Some work was technical and/or research-oriented. Other work was educational. As much as possible, activities are listed from east to west and from north to south.

Annual Report↗
USGS1994

Map adventures

Map Adventures, with seven accompanying lessons, is appropriate for grades K-3. Students will learn basic concepts for visualizing objects from different perspectives and how to understand /and use maps.

General Information Product↗
USGS1990

The next big earthquake in the Bay Area may come sooner than you think—Are you prepared?

Many of us breathed a little easier after October 17, 1989. The Lorna Prieta earthquake, 7.1 on the Richter scale, meant that the big one, talked about for decades, had finally happened. And, bad as it was, we had survived. There are two things wrong with that. First, Lorna Prieta was not the big one. It was a moderately big one, certainly destructive to some parts of the Bay Area, but nowhere near the size of the great San Francisco earthquake of 1906. Second, having an earthquake like Lorna Prieta has little to do with the likelihood of having another one on a different fault, somewhere else in the area. The inevitability of a damaging earthquake still confronts everybody in the Bay Area, and we still risk substantial damage. A new study, released in July 1990 by the United States Geological Survey, says that there is a 67 percent chance of another earthquake the size of Lorna Prieta during the next 30 years and that the quake could strike at any time, including today. In other words, scientists think that a magnitude 7 or larger earthquake is now twice as likely to happen as not to happen. This is a substantial increase, since in 1988, scientists thought the chance for such an earthquake was 50 percent Gust as likely to occur as not to occur) within 30 years. The new report also says that the next one will most likely strike farther north than Lorna Prieta, somewhere between San Jose and Santa Rosa on either side of the Bay. The epicenter of the October 1989 quake was in a sparsely populated area. The next one, according to the study, will likely be centered in a more populated area. During the Lorna Prieta earthquake, shaking was so severe in the Santa Cruz Mountains that a van overturned, treetops snapped off, and many people were thrown to the ground. Because the next one is expected to strike closer to an urban area, it will cause much more damage. Fortunately, there is something we can do about it. By taking actions, such as those described in this booklet, we can drastically reduce the losses and we can make the Bay Area a safer place to live. Earthquake damage is particularly great in certain locations and in certain buildings. Most locations and most modem buildings are relatively safe. By identifying the greatest hazards, we can set priorities for using our limited resources most effectively to reduce them. The choice is ours.

General Interest Publication↗
USGS1990

Metallic-mineral assessment of the Aban Al Ahmar quadrangle, sheet 25F, Kingdom of Saudi Arabia

Comprehensive detailed interdisciplinary study assesses the metallic-mineral-resource potential in the Aban Al Ahmar Quadrangle of the Kingdom of Saudi Arabia, located in the eastern margin of the northeastern Arabian Shield, utilizing techniques of geophysics, geologic mapping, remote sensing and geochemistry. The landscape of the study area is characterized by isolated mountain groups, inselbergs, and local tracts of dissected hills separated by broad, low-relief peneplain. Topics covered include mining and exploration history; geological setting; interpretation of geophysical anomalies; limonitic hydrothermally altered and mineralized rocks; geochemical interpretation; mineral resource potential; skarn deposiits associated with intermediate igneous rocks; gold deposits; tin/tungsten skarn deposits; etc.

Aban Al Ahmar quadrangle↗
USGS1985

National water summary 1984: Hydrologic events, selected water-quality trends, and ground-water resources

Water year 1984 was a year of extreme hydrologic conditions. For the third consecutive year, precipitation and resulting runoff were well above long-term averages in most of the Nation and as much as 400 percent above average in the Southwest. National flood damages during the year were the third highest in a 10-year period (1975-84) an estimated $3.5 to $4 billion. In many of the larger river systems, monthly stream discharges were above normal, as they have been for the last 2 water years, and, with the exception of a few reservoir systems, end-of-month reservoir storage also remained above normal. The Great Salt Lake reached its highest level since 1873 as a result of these conditions. During a 9.6-foot rise from September 1982 to July 1984, the area of the lake expanded by 600 square miles (an increase of 35 percent), resulting in an estimated $212 million in damages to recreational facilities and industrial installations built on the exposed lake bed during former lower levels. Other lake levels in closed basins of the Western United States also have risen over the past few years, thereby flooding communities, recreational facilities, and agricultural lands. In contrast to this predominant pattern of wet conditions, several areas of the country, mainly west Texas and Hawaii, have experienced persistent droughts. Most recently, very dry conditions existed in parts of northern Montana. These hydrologic conditions and 100 specific events are reviewed in the "Hydrologic Conditions and Water-Related Events, Water Year 1984" part of the 1984 National Water Summary .

Water Supply Paper↗
USGS1984

Offset of Tertiary arcs on the Alaska Peninsula: A section in Geological Survey research, fiscal year 1981

Geologic mapping and potassium-argon dating by R. L. Detterman, F. H. Wilson, J. E. Case, and Nora Shew in the Ugashik and western part of the Karluk quadrangles have shown that the Eocene and Oligocene volcanic arc continues into these quadrangles from the south in the Chignik and Sutwik Island quadrangles. Surface exposures of the arc extend northward to approximately 57°30'N., or midway through the Ugashik quadrangle, but none are observed north of that point. Subsurface drill-hole data (Brockway and others, 1975) indicate continuation of the arc, possibly offset to the northwest of the northernmost known surface exposures. In the extreme northern part of the Ugashik and Karluk quadrangles, volcanic rocks again become important. These volcanic rocks are as yet undated; however, they may be related to the Katmai late Tertiary volcanic centers. Like the early Tertiary volcanic arc, the present-day Aleutian arc is also offset to the northwest in the northern part of the Ugashik and Karluk quadrangles. No major offset of the Mesozoic rocks is indicated through the offset zone; this fact suggests a change in the Tertiary tectonic regime in the area of the offset.

Alaska↗