THE ODYSSEY OF PLANET EARTH

E. JULIUS DASCH

We are moving ever closer to unlocking the secrets
of Earth’s birth, life processes, and future

Earth sciences, covering a broad range of sciences related to Earth’s structure and genesis, are a relatively modern field of study. Certainly, considering that Earth itself is some 4.55 billion years old, earth sciences have been around for but a tiny blip on the evolutionary horizon, a mere 200 years or so. Within this short time-frame, tremendous advances have been made in understanding the solid Earth, its oceans, atmosphere, and living creatures, as well as planet Earth’s place in the solar system and the universe.

Prior to the late 18th century, the roots of geology were strongly intertwined with religion, natural history, and the extraction and use of such resources as coal, metals, and building stone. The realization early in the 19th century that Earth’s history is vastly longer than the biblical record was one of the great events of western science. James Hutton, father of modern geology, was foremost in unraveling the antiquity of rocks in his native Scotland. In 1788, long before the advent of radiometric dating of rocks, Hutton realized that enormous amounts of time were required to produce features like an unconformity, or break in the geologic record. He discovered that this break, or boundary, represented an immense amount of geologic time—time for the strata below to have been tilted and eroded, then overlain by waterlain strata deposited horizontally. Reconstructing the slow geologic events necessary to bring about this feature, he envisioned “...no vestige of a beginning, no prospect of an end” of geologic time.

The Darwinian revolution in scientific thinking of the mid-19th century, another major milestone, created a firm template for understanding paleontology and the way life has developed on Earth. This revolution radically redirected our view and understanding of both geology and biology. The discovery of fossils and the use of the fossil record to date geologic strata meant not only that evolutionary relations could be understood, but also that time-distinctive fossils could be used to unravel geologic events such as folding, faulting, mountain building, and erosion.

The Cosmos Club’s own co-founder, John Wesley Powell, was among those scientists and explorers who made major earth science contributions in the 19th century. Powell completed numerous assessments and scientific mappings of large tracts of the western United States by triangulation surveys, contributing to the understanding of the development of mountain and valley landforms. Legendary for his daring descent of the Green and Colorado rivers that ended successfully below the Grand Canyon in August 1869, Powell’s lasting legacy was his prescient analysis of land and water reforms necessary in the arid West, as well as his leadership role in the emergent US Geological Survey (see page 27).

NEW TECHNOLOGIES, NEW TOOLS

For Powell and his contemporaries, the scientific method was largely a matter of descriptive analysis: scientists explored, observed, and described their observations. During the 20th century, with the advent of new scientific methods, studies in earth sciences shifted from descriptive and qualitative works to analytical and quantitative endeavors. In the 1940s and 1950s, geologists, physicists, and chemists began to make fundamental analytical and theoretical observations about earth processes, including, for example, the crystallization of minerals from molten rock and the behavior of earthquake shock waves. Laboratory analysis and experimentation, combined with testable theoretical considerations, became important and necessary for a better understanding of Earth. A primary example of this descriptive-to-analytical shift is the quantification, by radiometric age dating, of the earth sciences’ most important cornerstone, the geologic time scale, which had been constructed from qualitative studies of faunal succession. For the first time, scientists could ascertain not only which strata of rock preceded another by visual analysis, but could actually test the rock sample, or its constituent materials, for radioactive decay rates and thus assign an absolute time of formation.

Perhaps the most dramatic breakthrough in earth sciences occurred in the 1960s and 1970s with the development of a quantitative basis for the theory of plate tectonics, which holds that large segments of Earth’s lithosphere, known as plates, move about on Earth’s surface relative to one another. This development provided a suitable mechanism for the drifting of continents, plate divergence (seafloor spreading), and plate collisions. Almost at once, disparate geologic topics, such as earthquakes, volcanism, mountain building, and the formation and placement of ores within Earth, became understandable as parts of a grand, unified model for earth processes.

But it took a further scientific and engineering breakthrough to see Earth in an entirely new light. By the late 1960s, the Apollo and Russian Luna missions provided the first photographs of Earth taken from space, providing profound new images of Earth as a unique but fragile world, a minute dot in the solar system and the vast universe. These new images of “Spaceship Earth,” revealing the planet’s wonderful colors, but perilously thin atmosphere, also provided startling evidence of humankind’s legacy. Photographs from the Apollo program and later space flights showed clear evidence of soil erosion and deforestation from clear-cutting and the burning of large segments of the world’s rainforests, a widening hole in the ozone layer at the polar regions, and ecosystems disturbed by air and water contamination.

The advent of space flight also enabled earth scientists to glean new knowledge about Earth by studying its neighbors in far greater detail than had ever been possible. In the past four decades, robotic missions to explore all the planets except Pluto, as well as a large number of the satellites of the outer giant gaseous planets, have documented striking and largely unforeseen differences between Earth and other major bodies in our solar system. Unsuspected variability among the planets and their satellites has been found. The same physical processes that operate on Earth also operate throughout our solar system (including landslides, volcanism, ice formation, folding, and faulting). But the data from these missions show a greater range of these conditions from one planetary body to another. Such variability results in moons and planets with strikingly different geologic aspects. Understanding this variability will help to unravel Earth’s evolution. The fabulous rocky and icy moons of Jupiter, for example, present clear records of geologic processes that can be compared and contrasted with those on Earth.

AT THE CROSSROADS

Earth sciences, which focus on the origin and evolution of Earth, are as much concerned with emerging issues as they are with understanding Earth’s past. And the field itself has evolved, particularly in the United States and in other industrial countries, where there has been a marked reduction in jobs related to resource extraction. In its place has come a shift to enterprises concerned with Earth’s stewardship and resource planning. In the United States, for example, petroleum and natural gas companies provided vast employment opportunities for geologists until the mid-1980s, when lower fuel prices meant a decreased emphasis on locating new oil and gas fields. At the same time, new observations about the degradation of the planet have opened new opportunities for scientists involved in environmental fields, especially water resources.

Dozens of important issues might be highlighted as “emerging,” including (1) Earth’s critically frayed ecosystems (freshwater, coastal/marine, agricultural land, forests, and grasslands) and the developing United Nations response to assess thoroughly the global health of these ecosystems and their sustainability; (2) global climatic change, both geological and anthropomorphic; (3) core-mantle-crust dynamics and the continuing understanding of plate tectonics; (4) planetary geology-geophysics (planetology) and ambitious, ongoing robotic and human exploration; (5) possible connectivity between asteroid/comet impacts and large volcanic fields; (6) advances in geochrononology; (7) earth science, society, education, and policy; (8) remote sensing and geographic information systems in the new millennium; and (9) instrumentation and analysis within the confluence of the developing fields of nanotechnology, biotechnology, and information technology. Representative of the very practical, as well as the cutting edge of research, are water resources, natural hazards, and paleontology/astrobiology.

Water resources
Seventy-five percent of Earth’s surface is covered by water, but less than one-half of one percent is suitable for human or agricultural needs. Unlike fossil fuels and metallic and nonmetallic ores, surface water is a renewable resource in the geologic sense, as it is continually replenished by rain and snow. However, the renewing in many locales is much too slow to balance the amounts of water withdrawn from surface reservoirs (streams, natural and man-made lakes, and off-channel storage), a finding forcefully made by John Wesley Powell. Groundwater (subsurface water) is replenished extremely slowly by seepage from rain and snow into aquifers, commonly less than an inch per year. But pumping these aquifers for agricultural or municipal purposes may lower groundwater tables several feet per year. Consequently, in many localities, this valuable resource, which has allowed the desert to “bloom” in the western United States, is being drained faster than it can recover. The resulting imbalance to users of this resource sets the stage for local, national, and global conflict.

Continuing the current trend in world population growth will result in a global population of 30 billion by the year 3000, five times the number for the year 2000. Although few demographers believe such an enormous number will be reached, owing primarily to better education and improved methods of birth control, most participants believe that a major threat to the future welfare of humanity is population growth and the concomitant increase in water needs. Human water consumption rose twice as fast as the rate of growth of the global population. Humans now use more than half of the readily available freshwater. Additional demands, assuming substantial rates of growth, will jeopardize other ecosystems.

Along with hydrologists and civil engineers, earth scientists play a large and rapidly growing role in the conservation, extraction, and management of water resources. An extensive and growing part of water management is in environmental protection and amelioration of such problems as anthropomorphic contamination, drawdown and resulting encroachment of seawater or natural brines, and the overuse of dams and off-channel storage. Extensive water table drawdown may cause major subsidence problems with highways, buildings, sewers, and waterlines. The critical issue for earth scientists is to help assure the quantity and quality of this most precious resource for humans, while maintaining or improving environmental integrity.

The Foundation for the Future, located in Bellevue, Washington, is among those organizations concerned with water and other resources. Established in 1996, the Foundation is concerned with the factors that may affect human life on Earth in the coming millennia, and has conducted several seminars on “Humanity 3000,” inviting scholars to address this topic. At one recent seminar, the just, efficient, and sustainable use of natural resources, particularly water, was ranked by many participants as the most critical issue facing society today.

Natural hazards and disasters
Spectacular, disruptive hazards and disasters that all too often are in the headlines include phenomena that fall within the domain of earth sciences. Floods, landslides, volcanic eruptions, earthquakes, asteroid impacts, tsunamis, and coastal storms are constant and violent reminders that Earth is continuously evolving. From the 1976 earthquake in Tangshan, China, which killed at least 300,000 people, to Hurricane Mitch in 1998, in which more than 10,000 lives were lost in Central America, natural hazards and disasters account for frightful costs in lives and property. Globalization of the world economy makes almost everyone subject to these events, not just the population at the scene of the disaster.

Considerable governmental effort is being placed on developing the technology and analytical models to improve our understanding of these natural processes. Ways to measure, predict, and, in some cases, actually prevent or mitigate these processes are being addressed, along with ways to help humans adjust to the threat and damage from these events. Earth scientists, long involved in the scientific understanding of earthquakes, volcanoes, landslides, impacts, and other geologic phenomena, also are increasingly involved with their impact on the public.

Improvements in instrumentation (chemical and physical analysis, seismology, satellite technology, and micro-electronics), coupled with the acquisition of vast amounts of information that can be rapidly stored, accessed, and communicated, have led to enhanced understanding of these processes. Although prediction and prevention have lagged behind data acquisition and analysis, progress is being made, for example, in assessing seismic and volcanic risk. Such distributed, multi-purpose, state-of-the-art sets of linked instruments and observations will open new opportunities to earth scientists in probing our planet.

The challenge is to develop and present innovative yet practical solutions to the problems faced by all sectors of the hazards-response community, including federal, state, and local governments, academia, the private sector, and non-governmental groups. This effort is required to bring together scientific, technical, policy-making, regulatory, and even social and behavioral disciplines, to confront the loss and cost reduction of natural hazards. Dealing with this challenge requires looking well beyond the boundaries of the traditional science disciplines. One group attempting to pull scientists, academics, and public and private interests together is the Public Private Partnership, which was established in 1997 to seek opportunities for these entities to work together to reduce vulnerability to natural hazards in the United States.

Paleontology and astrobiology
Always a pillar of classical geology, the discipline of paleontology has not afforded adequate numbers of jobs in the past two decades. With less emphasis being placed on oil/gas exploration and fewer jobs in the field, the intrinsic applied value of paleontology has lessened. This unfortunate situation is changing, thanks to the growing realization that the study of past life is critical to understanding our place in the cosmos. Certain aspects of the ongoing space exploration missions are among the most critical elements of the exciting, burgeoning study of the origin and evolution of life on Earth and in the solar system and universe.

Substantial discoveries in paleontology are made in increasingly greater numbers. Some examples include new insights into dinosaur evolution, history of flight, and human evolution. Perhaps the most breathtaking discoveries are being made in the understanding of the earliest forms of life on Earth and possible life elsewhere in the solar system and universe. One of the National Aeronautics and Space Administration’s newest initiatives, astrobiology, is the study of the origin, evolution, distribution, and destiny of life in the universe. Fundamental questions are being posed, such as how does life begin; does life exist elsewhere in the universe; and what is life’s future on Earth and beyond?

Astrobiology involves a wide range of disciplines. These studies focus, for example, on the essence of earliest and evolving life; the oldest Earth fossils (circa 3.8 billion years old) and their chemical and isotopic compositions; life in extreme environments; the continuing discovery of extrasolar planets; liquid water on early (and perhaps modern) Mars and on Jupiter’s moon Europa; and the effects of comets and asteroids on the evolution and extinction of life.

A fascinating example of modern research in Earth’s earliest life is the detailed biologic and geologic study of the earliest known sedimentary rocks, and the earliest evidence of biologic processes, in southwestern Greenland. These rocks, 3.85 billion years or older, formed on Earth at a time when many scientists believe that Earth’s moon (and Earth) experienced intense asteroid and comet bombardment, with accompanying thermal and shock effects. At this time, Earth was receiving a higher flux of ultraviolet radiation from the sun, as the limited oxygen in Earth’s atmosphere meant that there was little ozone to block solar radiation. These combined effects presumably would have limited the possibility of life arising on Earth, yet it appears that heat-loving bacteria may have survived, possibly in the depths of the oceans or subsurface rocks, somewhat shielded from the raining of cosmic debris. If true, this finding places the ancestry of primitive bacteria living in extreme environments near the common ancestor of all known life.

Other discoveries in recent years have dramatically changed our views of life in the universe. For example, more planets have been found outside the Milky Way than within. And the “habitable” zone for terrestrial life is much broader than had previously been thought. Life on Earth has been found to survive up to 5 Mrads of radiation, in temperatures of -15 to 113 degrees C, and in acidity levels of 0 to 11 pH. Life forms may even lie dormant for 20-40 million years, as discoveries of DNA within bees and other forms of life preserved in amber suggest.

THE VOYAGE CONTINUES

In 200 short years, earth sciences have progressed from rudimentary visual analysis of natural phenomena to quantifiable theories and explanations. Geology, which once focused on how best to extract ores and other natural commodities, has now become a highly integrated systems science that addresses most of the fundamental questions of the natural world. Additionally, the earth sciences occupy a critical position in modern society, bearing on issues of natural hazards, resource extraction (including extraterrestrial resources), environmental protection, scientific and technical education, appreciation of scenery, and cutting- edge research on subjects such as the origin, evolution, and destiny of life in the universe.

With the broadening of the earth sciences as a discipline, job opportunities for earth scientists have multiplied in the past decade. Opportunities abound, not only in the more narrow scientific disciplines, but also in related land-use management, law, insurance, and policy fields. Opportunities abound, too, in simply keeping the world up to date with all that is being discovered about planet Earth. In the United States, for example, a high percentage of the population is scientifically and technically illiterate. Addressing this matter of national concern requires better teacher preparation and in-service training, curriculum reform, better use of educational technology, and the development of national and state educational standards in mathematics, science, geography, and technology. An interdisciplinary approach to learning that incorporates science, mathematics, and technology can result in a more scientifically and technically literate populace. The earth sciences provide an attractive vehicle for this type of interdisciplinary training.

And, while geology and other earth sciences increasingly involve experimental, analytical, and computer analyses, the lure of fieldwork and new discoveries will always remain intense. As Sir Walter Scott noted in St. Ronan’s Well in 1824: “...and some rin up hill and down dale, knapping the chucky stanes to pieces wi’ hammers, like sae mony roadmakers run daft—they sae it is to see how the warld was made!” Whether with hammers, telescopes, or the latest computer models, getting to know planet Earth is a fascinating and, perhaps, never-ending process.

Additional Resources:

Mojzis, S.J., and Harrison, T.M. “Vestiges of a Beginning,” GSA Today,v.10, 2000.
Reisner, Marc. Cadillac Desert: The American West and its Disappearing Water. Penguin USA, 1993.
International Society for the Study of the Origin of Life web site [http://www.chemistry.ucsc.edu/~issol/].
NASA’s Astrobiology web site [http://astrobiology.arc.nasa.gov/index.cfm].
Natural Hazards Research and Application Center (University of Colorado at Bolder), international clearinghouse and research center web site [http://www.colorado.edu/hazards/intro.html].
US Department of the Interior, US Geological Survey web site, for information on water resources [http://water.usgs.gov/].

E. Julius Dasch (CC ‘99), currently NASA’s program officer for research and development, Education Division, received his Boy Scout merit badge for Rocks and Minerals at the age of 13, and never seriously considered any other profession. He has worked in exploration of oil, mineral, and groundwater resources, and has conducted research and taught at various universities. He also has served as editor in chief for Macmillan Reference USA encyclopedias, from which some of the material in this article has been adapted.

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