1920's - 1940's
The Division of Geological and Planetary Sciences began as the Department of Geology at Caltech in 1926.
The Seismological Laboratory existed before the formation of Caltech’s geology department, having been founded by the Carnegie Institution of Washington in 1921. After 1926, the lab was managed jointly by the Carnegie Institution of Washington and the California Institute of Technology, until administration of the Seismo Lab was transfered to Caltech in 1937. In the 1920's Charles Richter, a Caltech physics graduate working at the Seismo Lab, developed a formula for comparing the magnitudes of Southern California earthquakes. In the 1930's Beno Gutenberg joined both the division and the Seismo Lab, and he and Richter together developed the Richter Scale we use today. Hugo Benioff, also a division professor and member of the Seismo Lab, studied seismically active subduction zones or "Benioff-Wadati" zones.
Paleontologist Chester Stock helped to establish the principles of mammalian evolution. In addition to chairing the division for a period, he also served a chief science curator at the Natural History Museum of Los Angeles County. Many of the fossils he collected are now at the Page Museum.
The Charles Dayton Arms and Seeley W. Mudd Laboratories of Geological Sciences (Arms and North Mudd) were built in 1938.
1950's - 1960's
During this time, the division grew to include programs of study and research in geochemistry and planetary science.
The entry into geochemistry around 1950 was largely at the expense of paleontology and marked a remarkable transition to a more quantitative approach to earth science. The entry into planetary science in the 1960’s took advantage of the new U.S. space program of unmanned exploration and the proximity of the Jet Propulsion Laboratory. At that time, the division adopted its current name.
Geochemist Clair Patterson determined the age of the earth as 4.55 billion years, building on work begun at University of Chicago. He also studied the build-up of lead in the environment and in the human body, and his work in this area, which continued into the 1980's, contributed to the removal of lead from gasoline, food containers, and paint.
Paleoecologist Heinz Lowenstam discovered that some animals manufacture magnetic minerals in their bodies. Recently, researchers building on this work found that homing pigeons use magnetite in their beaks to help them navigate.
Robert Sharp and other geologists were taking long-range looks at the flow processes in the ice of glaciers, and people like Leon Silver were concentrating on the origins of the earth's very old rocks, particularly in western North America. Silver's work made him a natural for later training Apollo astronauts on what to look for scientifically on the moon.
1970's - 1980's
Scientists in the division did intensive work on the isotopes in various elements, developing and refining isotopic age-dating techniques that are applicable to many meteoritic, terrestrial, and lunar materials. They were responsible for key contributions to the analysis of lunar material and the interpretation of images and other data from many spacecraft missions. They made studies of the earth's climate using isotopic means and made possible a new understanding of both ancient climates and climatic changes over the last thousand years.
In addition to analyzing data returned to earth from increasingly sophisticated space exploration missions, planetary scientists contributed to the design of instrumentation to increase the power of existing telescopes. One—James Westphal—designed the Space Telescope's Wide Field/Planetary Camera. A combination of high-pressure experimentation and solid-state theoretical work improved understanding of the structure of the earth's interior.
The Seeley G. Mudd Building of Geophysics and Planetary Sciences (South Mudd) was built in 1974, and this marked the move of the Seismological Laboratory onto campus from its previous location at the Kresge laboratory.
1990's - today
During this period, the division expanded in new directions, building strong programs in geobiology and in environmental science, including atmospheric science and oceanographic activities that were previously not present at Caltech or were only to be found in the engineering and applied science division. This growth in strength has taken advantage of collaborative efforts, including joint appointments, with other divisions. It has also benefited from existing and sustained strength in geology and geochemistry.
Although geobiology has had a long association with Caltech, through the pioneering efforts of Lowenstam and the subsequent research of Joe Kirschvink (particularly on the role of magnetism), the division recognized the importance of biology in Earth evolution and successfully sought to build this area. The division has also established a Tectonics Observatory, shown leadership in computational geophysics, and played a leading role in the discovery of dwarf planets, including a body larger than Pluto.
A remarkable feature of the division in the past decade or so has been the hiring of more than half the current faculty as older faculty have graduated to emeritus status. Our young group of highly active, influential and successful young scientists attest to the continuing vitality and world leadership of the division.