The Earth and Planetary SciencesToday
A characteristic feature of the Earth and planetary sciences is the integrated nature in which a set of disciplines focuses on the study of the Earth and its processes. Earth scientists are united by the problems they attempt to solve rather than by work methods and techniques. Geologists study the products of the past and current natural events, deduce the processes behind them, and analyze the events, their causes and consequences in time. They investigate the Earth from planetary scales to submicroscopic and atomic scales in their search for understanding our planet's origin, history, and evolution. The Department of Earth and Planetary Sciences includes active participants in many different fields of research. Techniques and tools used in the studies of the Earth embrace a full spectrum of research technology, including remote sensing, direct observations, and laboratory and computer-based analyses. The first step towards the understanding of geological processes is to investigate them in the field. Members of the department observe volcanoes, igneous bodies, mountains and rift valleys, earthquakes, ocean and lake waters, sediments and paleofaunas, and other planets and extraterrestrial bodies, augmenting these observations by laboratory studies of natural materials. The faculty and students' research in the field has included many locations, and the map of the world in this section shows the more recent and ongoing research sites.
The Earth is a dynamic, ever-changing planet. Many of the ancient processes that formed our landscape are also occurring today, albeit at rates which are nearly imperceptible. The great plates that carry the continents in their drift over the Earth's surface move at the rates of only 2 to 10 cm a year. The complex processes involved in past changes of the Earth's climate are also at work both on the very slow, geologically long time scales, as well as on the time scales of decades to centuries, shaping our environment through natural processes and the effects of human activity.
The department's environmental research includes studies of the environments in the more distant geological past, studies of the geochemical processes and geochemical cycles under natural and perturbed conditions, and analysis of the timing and driving mechanisms of the major climatic trends and ice ages. Our research into the movements of continental and oceanic plates on the Earth's surface includes field studies of their boundaries, analysis of the Earth's magnetic field through time, studies of earthquakes occurring in different geological settings, and studies of the modern and ancient sediments. Research on the Earth's interior is being conducted by laboratory experiments simulating the high pressures and temperatures at depth, theoretical studies of the composition and properties of the interior, and analysis of seismic waves traveling through the Earth.
Geophysics is, literally, the physics of the Earth. Geophysicists apply the techniques of mathematics and physics to understanding Earth processes. Much recent research has focused on plate tectonics. Paleomagnetism, which describes the history of the Earth's magnetic field as recorded in rocks, can be used to deduce the movements of continents and oceans through time. Seismology, the study of elastic waves that travel around and through the Earth, is used to study the positions and movements of the plates on the Earth's surface. Satellite Laser Ranging and Long Baseline Radio Interferometry are new and powerful tools to measure plate motions. A vast body of knowledge based on the physics of solids and fluids bears on the studies of the history of ice sheets and of the paleoclimates. Geophysical methods are used in practical applications as well as in pure research. The major tools used in exploration for resources, especially petroleum, are geophysical. Resource exploration will continue to be one of the major challenges in the coming decades. Geophysical techniques are the main tools in the studies and prediction of such environmental hazards as earthquakes, tornadoes, tsunamis, and volcanic eruptions.
The application of chemical principles to the study of the Earth and solar system, as well as the investigation of the chemical processes on Earth, falls into the domain of geochemistry. The Earth is a natural laboratory where mineral and chemical reactions are continuously taking place, from the very high temperatures and pressures of the Earth's interior to those of the Earth's surface. Rocks melt and produce magmas and lavas; these, in turn, crystallize in an amazing plethora of ways, making new rocks; rocks are weathered and eroded producing new minerals and adding dissolved materials to rivers, lakes and seas; waters evaporate changing the composition of the atmosphere and leaving behind mineral residues. It is the task of the geochemists, petrologists and mineralogists to identify and understand these processes. One aspect that is unique to geochemistry is that it provides information about chemical processes, which cannot be reproduced by man. Very slow reactions, which can take millions or even hundreds of millions of years, can be observed only in the natural laboratory. Chemical processes also play a crucial role in determining the climate of the Earth, for example through the carbon cycle. Inorganic and organic geochemical techniques are widely used in exploration for mineral and fuel resources.
Our ability to predict the geological future, on the time scales from very short to long, greatly depends on our understanding of the evolving past and the present of our planet. This is particularly true for the changing climate of the Earth. For example, new sediment records from the deep sea tell us much about the ice ages of the last few million years, and the atmospheric gases entrapped in ice tell us about the changing composition of the atmosphere in the last 200 000 years. Coupled with mathematical models of the Earth system, this knowledge of the past can lead to a prediction of the future climate changes of the Earth.
The Earth and planetary sciences are a very special amalgam of theory, observation, and laboratory research, requiring scientific skills and knowledge from several disciplines. Students with a variety of backgrounds and aptitudes should find it academically rewarding to join the department, as long as they have curiosity about natural processes. Students who enjoy working outdoors, making careful observations, or who have a good aptitude in mathematics, physics, computer science or chemistry can find a rewarding career in the geological sciences.