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research collections are restricted in a museum.

The USGS WWW Library is accessed through its front door, which is called the USGS Home Page. Upon entering the library, the user is presented with several options to help find the information desired. Most users will probably be one of three types: general public, student or teacher, or research scientist. Different areas can be provided on the Home Page for each type of user.

The Home Page consists of four major areas: (1) a navigational tool for finding information, (2) a short introduction to the USGS, (3) a menu of options for using the resources of the library, and (4) information on how to contact the USGS. A user needs merely to click a mouse button on any of the underlined words or phrases to be shown the new page of information selected.

A variety of USGS information is currently available on the Internet. Many publications, including some written for a general audience, are available. Job announcements and news releases are regularly posted and updated. Many data sets are available for direct downloading or can be ordered on the network for delivery in other formats. The list of available information is growing as USGS customers become aware of this service.

A “visitors center" is being added to the USGS WWW Library to guide the public on tours through the USGS. These predefined paths through the body of information available from the USGS on the Internet will make the service more useful and entertaining for the public, especially students and teachers. Sample tours will include “Geographic Information Systems,” “Earthquake!", and “The Water Cycle.”

The USGS WWW Library has been available on an experimental basis since June 1993. During the 1-year period from June 1993 to June 1994, use of the service grew at about 20 percent per month. More than 10,000 people per month are now accessing more than 100,000 pages of information per month, and use of the service continues to expand.

The Internet has become a crucial tool for disseminating USGS information and products in fulfillment of the USGS mission.

William Miller studies computer systems and their application to the earth sciences.

GeoMedia2 Shows the Wonder of Earth Science

he best teachers are those who instill a

sense of wonder in their students— whether about earth processes, the evolution of life, or the rise and fall of ancient civilizations. Evoking curiosity about the Earth continues to challenge educators, particularly as science literacy has declined in the United States. As environmental issues become more complex, the country needs informed citizens capable of making decisions and voting on legislation about natural resources and hazards and planning for the 21st century. Legislation known as “Goals 2000: Educate America” calls for assistance to States and local communities in meeting the President's education goals. Making the United States first in the world in math and science is one of the goals of this legislation.

To meet these educational challenges, the U.S. Geological Survey (USGS) has been exploring new ways of communicating earth science topics to pre-college students. Through a long-term research and development project, the USGS has been assessing the effectiveness of teaching earth science through the use of hypermedia, a computer technology that allows users to choose their own path through information in a variety of formats.

In 1991, the USGS began to develop its first earth science computer system based on

text, graphics, animation, and sound.

The concept of hypertext, also known as hypermedia, was first proposed in 1945 by one of the first computer scientists, Vannevar Bush, in an article titled "As We May Think," which was published in the Atlantic Monthly. Bush envisioned a device called the memex where all types of information, such as books, pictures, records, and letters, could be stored. Bush imagined that the information could be accessed in a nonlinear method more closely aligned to cognitive processes by creating links between associative material. The term was popularized by Ted Nelson, a leading proponent of hypertext technology, in 1965. Today, hypertext has come to mean a software environment for creating nonsequential database management systems. Hypertext techniques provide the capability to create associative links between structured and unstructured information that may include

Computer screen from GeoMedia2 showing table of contents.The application was designed for Apple Macintosh computers and developed by using Macromedia Director authoring software, which is produced by Macromedia, Inc.

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hypermedia technology. The objective of this research and development project was to design and implement a hypermedia educational system aimed at middle-school students. The project resulted in the development of a prototype entitled GeoMedia, which presents information on the water cycle, earthquakes, and understanding maps. Each of the three modules contains animations, illustrations, text, a glossary of terms, and a reading list. GeoMedia was distributed on digital compact disc to earth science teachers in the United States from 1992 to 1994. To date, approximately 2,500 discs have been distributed to educators who agreed to participate in

GeoMedia Computer Configuration Requirements

Macintosh

Macintosh suite of computers with System 7.0 or later 13-inch or larger color monitor 5 megabytes of memory CD-ROM drive

Windows

In 1995, GeoMedia (volumes 1 and 2) will be replicated for Windows. Configuration requirements for computers running Windows have not been determined at this time. Additional information on these forthcoming products is available from the authors of this article or InterNetwork Media, Inc., at the address listed below.

Address inquiries about purchasing GeoMedia discs to:

InterNetwork Media, Inc. 1130 Camino Del Mar, Suite H Del Mar, CA 92014

the project by evaluating the information on the disc. Favorable responses to GeoMedia from USGS employees and the educational community led to the development of a second hypermedia system on global environmental change. Again, the targeted academic level is middle school. The basic design of GeoMedia2 is patterned after the original system—a tour of earth science topics with video-game overtones. GeoMedia2 includes three modules: the carbon cycle, the greenhouse effect, and the monitoring of environmental change over time. The graphical user interface is the same but incorporates a few modifications based on teacher evaluations of GeoMedia. The modules each contain four sections: animation, elements, glossary, and further reading. The carbon cycle module illustrates the movement of carbon through the environment and the effect of human interactions on the cycle. The greenhouse effect module explains a natural environmental process that traps heat in the lower part of the Earth's atmosphere to keep the planet warm enough to sustain life. In the time and change module, students

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learn about the geologic history of the Earth and the evolution of living organisms. GeoMedia2 focuses on the many changes that have occurred throughout the 4.5-billion-year history of the Earth in the physical, chemical, geological, and biological characteristics of the planet. The USGS multimedia educational team will continue to distribute GeoMedia2 to teachers participating in the project until the fall of 1995, when both volumes will become available commercially.

Plans are underway to develop a hypermedia system that enables students to navigate through a nonsequential arrangement of information and further participate in the creative process by authoring their own multimedia reports. This application will explain earth science processes that relate to natural hazards, such as volcanoes and earthquakes. Students will explore earth science topics by selecting geographic regions that are notable for natural hazards. The approach to the information will be by using maps and satellite images instead of picking topics from a table of contents, which was the approach used in GeoMedia. The USGS expects to complete this prototype by the winter of 1996.

The USGS continues to design software that is in concert with national curriculum standards and reform movements, such as Project 2061 sponsored by the American Association for the Advancement of Science (AAAS). The AAAS emphasizes several key concepts for teaching science in a report entitled “Science for All Americans.” Among the principles of learning discussed in the report are two key philosophies embraced by the team during the software design process: (1) do not separate knowing from finding out and (2) science teaching should reflect scientific values by welcoming curiosity, rewarding creativity, and encouraging a spirit of healthy questioning.

Denise A. Wiltshire is a writer and information scientist currently serving as a multimedia producer for the USGS,

Carmelo F. Ferrigno is a USGS computer scientist specializing in scientific data visualization and multimedia application development.

Using Geographic Information, Image Processing, and Animation Systems to Visualize a Digital Terrain Flyby

To flyby animation tools are being used by the U.S. Geological Survey (USGS) and other agencies such as the National Aeronautics and Space Administration, the National Oceanic and Atmospheric Administration, and the Department of Defense to analyze terrestrial and extraterrestrial data and to showcase data. To reduce the costs of buying analytical software to construct and view these animations, a multidivision, multiagency technology assessment project focused on integrating readily available commercial geographic information systems software (ARC/INFO), free image processing software (Khoros), and low-cost terrainrendering software (Surveyor) to merge several USGS data sets and produce terrain flybys.

The merged data sets included a digital orthophoto quadrangle (DOQ), a digital elevation model (DEM), and the transportation and hydrography digital line graph (DLG) layers for a mountainous area in Idaho. The DOQ data are a photograph of the Earth's surface. The DEM is a series of regularly spaced elevation points for this same area. The DLG is the line data from the digital data used in the production process of the USGS paper maps. Preprocessing of the data was performed with ARC/INFO software. After merging a DOO image and the DLG images, computer scientists used routines constructed in Khoros to produce red, green, and blue images, which were then reformatted for input to Surveyor. Surveyor software was then used to produce several DOQ and DLG terrain flybys. Integrating the three existing software packages and using the best features of each saved money by eliminating the need to procure a single equivalent expensive software package

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he transport of water and its properties

are governed by the laws of mass, momentum, and energy conservation. These laws have been translated into equations that, in turn, have been coded as Fortran computer language routines in a computer model called ECOM-si. This model is used by the U.S. Geological Survey (USGS) to investigate the flow of water and transport of waterborne constituents in the coastal ocean. Most recently, for example, it has been used to answer questions related to the construction, placement, and operation of a new sewage treatment plant and ocean outfall for the city of Boston, Mass. Specifically, ECOM-si is used to predict time and space dependencies

of water properties such as surface elevation, velocity, temperature, salinity, and dissolved constituent (for example, nonreactive dye released at the Boston outfall site) concentration as functions of winds, precipitation, atmospheric heating and cooling, tides, and river inflows. ECOM-si is a three-dimensional, time-dependent, finite-difference hydrodynamics circulation model that uses a curvilinear coordinate system to define a spatial domain consisting of discrete cells. The computer program calculates velocity, temperature, salinity, and dye concentration for every cell in the grid at evenly spaced intervals in time called time steps. In the Massachusetts Bay study case, the model runs on a grid of 68x 68x11 or roughly 50,000 cells representing the bay and Boston Harbor. This grid provides spatial resolution of 600 to 6,000 meters horizontally and 30 centimeters to 14 meters vertically. The model's time step is roughly 6 minutes. Use of the model can be time intensive. Computer simulations of 1 year of dissolved constituent transport take roughly 10 days to complete on a Sun SPARC station 2, 3 days on an IBM RISC 6000 model 580, 0.8 day on a Cray X-MP, and 0.15 day on a Cray C90 single central processing unit (CPU) system. To make calculations at finer spatial and temporal scales, which some coastal

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circulation problems require, and to make calculations over longer simulation periods without extending the total length of time required to complete the calculations, new techniques for solving the model's equations must be explored. One promising approach for accelerating these computations is splitting the model's

computations over multiple processors (paral

lelizing the model). For example, the model's computations can be divided for distributedmemory multicomputer systems such as the Thinking Machines Corporation's (TMC) Connection Machine CM-5. A CM-5 uses multiple processors to execute a parallel pro

gram. This program typically consists of sepa

rate tasks running on separate processors. All processors can execute the same task for independent data sets or different tasks for a single data set. In any case, a processor may have to communicate data—that is, send or receive the results of computations to or from another processor—to proceed with its own calculations.

To perform a large-scale circulation sim

ulation on a distributed-memory multicomputer, the serial computation can be split “in time,” “in space,” or both. An example of time splitting is dividing the problem so that each parallel processor performs the

Three-dimensional perspective view of the ECOM-si model grid for Massachusetts Bay as viewed from south to north. Cape Cod is in the foreground, and Boston Harbor is in the background on the left. ECOM-si calculates temperature, velocity, salinity, and dye concentration as a function of time in each of the roughly 50,000 grid cells shown in the figure.

calculations for a given month of a year-long simulation. This procedure is clearly inefficient, because each month's result depends on the previous months' results; consequently, a processor has to sit idle while waiting for the previous months' processors to finish. Space splitting has the potential to be much more advantageous. In space splitting, subsections of the model grid are distributed to the processors, and calculations for all the subsections are performed simultaneously. There remains a need for adjacent subsections to communicate information to one another, so processors must be able to communicate during the calculation process. The efficiency of this communication is a key to achieving good parallelization of the ECOM-si code. At present, the focus of the research presented here is on this spatial partitioning of the ECOM-si model grid; the Massachusetts Bay model is being used as a test Case. Automatic parallelizing compilers typically do not convert existing serial code into optimally efficient parallel code. However, the process of recoding a serial program is made simpler by such parallel languages as Fortran 90 or TMC Fortran, both of which are well suited for scientific computations. These languages permit a single operation,

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