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The USGS first obtained gravity data concurrent with the Doppler satellite observations with a La Coste-Romberg gravimeter in 1985–86 in the Beardmore Glacier area. During 1986–87, gravity data were collected in the Dry Valleys area; these data will be extended during 1988–89.

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Location of selected stations and physical features in Antarctica.

Cooperative Programs

sat 1:250,000- and 1:100,000-scale image maps of the Siple Coast and experimental Systeme Probatoire d'Observation de la Terre (a French satellite) 1:50,000scale image maps of selected areas.

In 1988–89, the USGS plans to acquire 150 Landsat Thematic Mapper scenes for the entire coastal area of the Antarctic continent. This imagery will be used for comparison with the Landsat multispectral scanner data of the early 1970's to assess any changes in the margin of Antarctic coastal features, which might reflect climatic change, and for other scientific applications.

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Atlas of Antarctic Glaciers

The first published chapter in an inventory of the world's glaciers being coordinated by the USGS focuses on Antarctica and provides scientists with a means to monitor changes in the margins of this icy continent that may be linked to climatic changes.

The satellite-image atlas of Antarctica is the first chapter in an 11-part series, "Satellite Image Atlas of Glaciers of the World,” being produced by the USGS as Professional Paper 1386. Each chapter or subchapter is authored by one or more of the 50 scientists from 30 countries who have collaborated on the atlas project.

The enormous area of ice concentrated in the glaciers of Antarctica-about 5.3 million square miles, including about 91 percent of the total volume of glacier ice on Earthinfluences the temperature, wind, and weather patterns over the entire Earth. Changes in the volume and dynamics of the ice sheet, therefore, may cause global climate changes. In turn, changes in the temperature of the planet can affect the volume and dynamics of the Antarctic ice sheet.

Certain glacier features are unique to the Antarctic. For example, nearly half of the coastline of Antarctica is fringed by “ice shelves,” floating ice sheets that rise and fall with the tide. They are nourished partly by the seaward extension of land glaciers, partly by the accumulation of snow on their upper surface, and partly by bottom freezing. They are dissipated mainly by the calving of icebergs from their seaward edges.

Byrd Glacier in the Transantarctic Mountains is one of the largest valley glaciers in the world and possibly the most active glacier draining any part of the East Antarctic plateau. Byrd Glacier drains an area of 393,000 square miles, greater than any other glacier in the world. Flow features on its surface can be traced over a distance of 112 miles.

The accompanying figure shows two Landsat images acquired before (November 11, 1973) and after (October 18, 1986) a major calving event on the Filchner Ice Shelf.

The size of the newly created icebergs totalled more than 4,000 square miles, or slightly less than the State of Connecticut.

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Survey and Land Information, to prepare 15-minute, 1:50,000-scale topographic quadrangle maps.

Scientific Committee on Antarctic Research (SCAR) Library

The USGS houses and maintains the SCAR Library for the National Science Foundation at the USGS National Center in Reston, Va. The library serves as the repository and distribution point for all Antarctic photographic and cartographic materials produced by the United States and materials distributed by other SCAR nations. Plans in the near future are to reinventory the library's holdings of geodetic control records, satellite images, aerial photographs, maps, charts, and publications and to encode the information into a series of digital data bases to better serve the Antarctic scientific community.

Antarctic Lakes: Biogeochemistry of Dissolved Organic Material in Lakes in the Dry Valleys By Diane M. McKnight

organic-geochemistry researchers has been to understand the relationship between the sources of these acid classes and their chemical structure and reactivity. Dissolved organic material from many diverse aquatic environments has been isolated, characterized, and compared. A particularly important question is whether the dissolved organic material in the world's oceans, which is a significant global carbon reservoir, is derived chiefly from land-surface runoff or from marine plant life.

The permanently ice-covered lakes in the McMurdo dry valleys of southern Victoria Land in Antarctica provide an excellent opportunity to study this problem because their watersheds are extremely barren and have only a few isolated patches of moss as their vegetation. In contrast, abundant algal populations develop in the water column of the lakes during the austral (southern) summer, and algal mats cover the bottom sediments. During the 1987–88 austral summer, USGS research scientists conducted a field study of dissolved organic material and microbial populations in Lake Fryxell and Lake Hoare in the Taylor Valley. Logistical support in Antarctica was provided by the Division of Polar Programs of the National Science Foundation under the Biology and Medical Sciences Program. To obtain sufficient quantities of organic material, large volumes of lake and stream water (as much as 480 gallons) were filtered to remove particulate matter; the filtrate was collected in stainless steel milk cans and processed at a field laboratory on the lakeshores. In addition, chemical constituents, dissolved gases, and rates of microbial processes were measured both onsite, by methods such as gas chromatography, and in the research laboratory at McMurdo Station.

Initial interpretation of the field data indicates that the main source of dissolved organic material in these lakes is degraded algal material in the anoxic (oxygen-less) lake sediments. In Lake Fryxell, for example, the concentration of dissolved organic carbon increased with depth, from values of 3 milligrams of carbon per liter just below the ice cover to values of 25 milligrams of carbon per liter above the lake sediments. The acid samples are being characterized

In temperate lakes and streams, dissolved organic material is derived both from the plants and soils of the surrounding watersheds and from the microscopic algae in the water and larger plants along the shores. This dissolved organic material is a heterogeneous mixture of organic compounds consisting largely of two classes of organic acids, fulvic acid and hydrophilic acid. These two organic acid fractions are geochemically and biologically reactive, and they significantly influence the chemistry and transport of many organic pollutants and trace-metal contaminants; they also hinder the proliferation of algae by absorbing the wavelengths of light required for growth. A long-term goal of the USGS

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by many different analytical methods, including elemental analysis and nuclear magnetic resonance spectroscopy. Results from these analyses will be used to test hypotheses about the formation pathways of fulvic and hydrophilic acids from algal material and will allow comparison of these microbial samples with samples from other aquatic environments.

Modern Analogs of Coal Formation

nation but also provide much-needed comparative information for research on domestic coal.

Under the proper geologic conditions of burial pressure, temperature, and time (usually millions of years), peat is transformed into coal. Therefore, studies of areas where peat is now forming, such as the current program, provide basic scientific data for determining the geologic factors that control the occurrence, quantity, and quality of coal beds. The data derived from this study may contribute to (1) more efficient and costeffective methods in coal exploration and resource and reserve assessments; (2) improved methods in mine planning based on new information on geologic controls on coal-bed thickness and geometry; and (3) new technologies in coal preparation and use based on new information on the geologic factors that control the chemical and physical properties of coal.

Previous work by the USGS has shown that much of the coal resources of the 48 conterminous States formed in tropical or subtropical environments. The Republic of Indonesia is an ideal location for a modern analog study because of the apparent similarities between coalbearing strata in the North American and Indonesian rock record and condi

By C. Blaine Cecil

The U.S. Geological Survey, in cooperation with the Directorate of Mineral Resources of the Republic of Indonesia, recently began a three-phase program to study peat deposits, which are modern analogs of coal-forming environments. These studies are conducted in a variety of geologic settings in various parts of Indonesia (fig. 2). Phase one was completed in 1987, phase two was conducted during the summer of 1988, and phase three will begin in July of 1989. These studies not only provide significant international benefit in assisting another

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Figure 2. Study areas for the 1987 and 1988 field seasons and the area proposed for 1989.

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tions of peat formation there today. In Indonesia, vast peat swamps cover thousands of square miles of lowland environments. Thick deposits of peat (as thick as 40 feet) of excellent quality (less than 0.3 percent sulfur, less than 3.0 percent ash, and about 10,000 BTU dry basis) are present over vast coastal areas. In this tropical, equatorial setting, rainfall is high and evenly distributed throughout the year. As a result of these conditions, weathering is intense and nutrients are depleted from upland soils. Because of the intense weathering, most of the rivers that traverse the peat swamps contain very little sediment (tens of parts per million). Peat can form because of the high rainfall and extremely low input of sediment into the depositional basins.

Approximately 18,000 years ago, during a lower stand of sea level, the continental shelf of the region was exposed as a large land mass (fig. 3). At present, the sea covers the continental shelf, which results in an extensive shallow sea and the drowning of the mouths of rivers, thereby creating estuaries. The extensive coastal plain environment is partly the result of these sea-level changes and partly the result of colliding

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