An eclectic hypothesis regarding processes and sources of energy governing the transformation and deformation of the earth’s crust is offered for study. Relatively light, sialic continental segments of the earth’s crust, essentially sedimentary in origin, have grown from small centers or lineaments to their present size, throughout geologic time. The physico-chemical instability of an original simatic crust of the earth beneath an atmosphere and hydrosphere—an instability stemming from the sun’s radiation—results in weathering, physical and chemical sorting, sedimentation, loading and depression of the ocean floors, unloading and uplift of the continental segments with deep burial of sediments, their deformation, metamorphism, and finally ultrametamorphism with the formation of the diorite-granite suite of plutonic intrusives, largely derived from sediments, but receiving accessions of simatic invasions through geologic time. Isostasy is a dominating link in this evolution. Thus, of all the discontinuities within the gravitational field of the earth, the most important is regarded as that between the atmosphere and hydrosphere above and the lithosphere below. The density distribution within the earth indicates gravitational adjustment during the early stages of the earth’s evolution when temperatures were higher and the subsurface was more mobile. The earth’s figure, an oblate spheroid of revolution, fits the observed density distribution of an earth wherein there prevails essentially hydrostatic stress distribution from the center outward almost to the surface. This stable figure of equilibrium has been maintained for billions of years and is being maintained today, against disturbing forces, in the region of the M discontinuity. The imbalance between light sialic, essentially sedimentary continental segments of the crust buoyed up dynamically by the heavier simatic segments of the ocean basins results in stresses directed toward the ocean basins, in spreading of continental segments, and in their invasion by simatic magma. Creep of heavy simatic material from beneath the ocean floors toward and beneath light, eroded, rising continental segments pari passu with depression of ocean floors or continental borders by geosynclinal loading results in stresses partly directed toward the continents. This directed stress is opposed by that residing in continental creep toward the ocean basins. Thus a stress couple initiates thrust faulting, gravitational sliding, extended deformation of geosynclinal depressions, and also invites volcanism. Thus many volcanic island arcs are linked in origin with geosynclinal depressions and illustrate progressive capture of ocean basins by continental segments, as the geosynclinals are folded, metamorphosed, and progressively uplifted. The intercepting, fringing Asiatic arcs are illustrations of this world-wide process. Volcanism is linked to the potential energy of the earth’s residual heat, to gravitation, to the effects of the temperature-pressure gradient on melting of rocks, and to imbalance between continental and oceanic segments. Volcanism on the ocean floors implies subsidence of these floors. The concentration of useful and precious metals is linked to the evolution of continental segments. Likewise the concentration of radioactive minerals in sedimentary rocks and sialic intrusives. The processes of continental evolution outlined imply continuous deformation of the earth’s surface, in time, but not in place.

Abstract Some years ago a group of geologists led by Professor C. R. Longwell of Yale University and Professor A. I . Levorsen of Stanford University proposed to honor Dr. Charles Peter Berkey, Newberry Professor Emeritus of Columbia University, for his life-long contributions in the field of engineering geology, by assembling and publishing a number of original papers each of which would deal with a special facet of the subject. The Geological Society of America, through its President Dr. N. L. Bowen, appointed a committee to carry out this proposal and agreed to publish the symposium. Dr. W. O. Hotchkiss was duly appointed Chairman of a working group, among whom were Sidney Paige, W. S. Mead, J. P. Buwalda, and B. C. Moneymaker. The authors, each selected for his particular knowledge in the field, have given generously of their time. I t was agreed that broad principles, rather than engineering or geologic detail, should be emphasized, but aside from this broad consideration each author was to prepare his material independently. To them all our thanks are due. It is doubtful whether these papers need further introduction. Each is addressd to a technically trained audience and is planned to emphasize principles, rather than the minutiae of engineering and geologic practice. The title of the boor– The Application of Geology to Engineering Practice –is self-explanatory and is well understood by engineers and geologists.

Abstract Charles P. Berkey became a geological consultant to the Bureau of Reclamation in 1928 just as the proposed Hoover Dam was passing into the stage of final study. The design and construction of Hoover Dam imposed new and unprecedented technical problems involving grave decisions and heavy responsibility. Everything about Hoover Dam was big–huge tunnels were planned, enormous amounts of concrete aggregate and excavation were required; the great height and weight of the proposed structure would load the foundations beyond engineering precedent; the water weight on the reservoir floor might cause the subsidence of a large surrounding area; the seismicity of the region required sharp appraisal and integration with the engineering design; the possibility was recognized that the weight of the dam and water might generate new stresses sufficiently large to stimulate seismicity–to mention only a few of the many Hoover Dam problems requiring both geological and engineering insight.

Abstract The branches of engineering most profoundly affected by geological factors are mining, petroleum, and civil engineering. The value of the professional geologist in mining and petroleum engineering has long been recognized, and no review of achievement is necessary to establish his important place in these fields. But it is only within comparatively recent years that the change has come which recognizes that an experienced engineering geologist is an essential part of an organization engaged in locating, planning, and constructing large civil engineering projects. This change has resulted, primarily, from two influences: (1) the large and growing demand of the civil engineering profession for a better understanding of the geologic factors involved in heavy construction–particularly the building of dams and allied hydraulic structures, and (2) the increasing ability of the geologist to apply his science in terms of engineering requirements. With this change, the demand for professional geological services has grown from an occasional call for advice from the consultant to the full-time utilization of large geologic groups composed of personnel trained and equipped for service in the civil engineering organization. Today, most engineering organizations engaged in heavy construction are alive to the fact that competent study and development of geological conditions employing the most modern techniques and tools in the hands of experienced investigators are required to give reasonable assurance that the geologic factors have been adequately developed and met.

Abstract The last 15 or 20 years have witnessed outstanding progress and major developments in the application of geology to civil engineering. Perhaps the most noteworthy field in which geology is essential to sound engineering is in the investigation of dam and reservoir sites, because the apprehension of the engineering problems resulting from geologic factors and the gauging of the ultimate effects of construction on natural conditions are major considerations in all river-development undertakings. “The construction of a dam to retain water causes more interference with natural conditions, than does any other civil engineering operation” (Legget, 1939). Therefore, with the advent of the large program of dam construction entered upon by the Federal Government about 1930, it was natural that attention should be directed to geological considerations and that much stimulus should be given to the ways and means of providing better and fuller geological information.

Abstract The early years of the century mark a period of great activity and growth in this country, with the City of New York sharing in the building boom which required the construction of highways, subways, aqueducts, and many other utilities on a large scale. I t was at that time, almost immediately after joining the geological staff at Columbia, that Doctor Berkey became identified with this work, and his many reports are famous advisory documents, particularly in connection with tunnels used for aqueducts, transport, and other purposes. His knowledge of geologic principles, facility in critical observation, hard common sense, and ability to state a case in useful, practical and simple terms have all contributed to a unique reputation.

Abstract The term landslide refers to a rapid displacement of a mass of rock, residual soil, or sediments adjoining a slope, in which the center of gravity of the moving mass advances in a downward and outward direction. A similar movement proceeding at an imperceptible rate is called creep. The velocity of the masses involved in a typical landslide increases more or less rapidly from almost zero to at least 1 foot per hour. Then i t again decreases to a small value. By contrast, typical creep is a continuous movement which proceeds at an average rate of less than 1 foot per decade. Higher rates of creep movements are rather uncommon.

Abstract Faults are ruptures in rock masses that are accompanied by differential displacement of opposite sides of the resultant fractures or fracture zones. They are therefore likely to be of serious concern to the engineering geologist.

Abstract Among the great engineering achievements of the last hundred years those relating to the development of water supplies are outstanding in their magnitude and in the high quality of service and results obtained. This is true in regard to public water supplies and the supplies for irrigation, industries, and other uses. I t is true for the United States and also for other parts of the world.

Abstract One of the most important problems before this country today is the construction of highways. This condition will last just as long as 3J million miles of highways continue to be the capillaries in the transportation system in which the railways are the arteries. These highways are essential to the economic and social development of the country, and it is the duty of technical men to make every possible contribution to this work.

Abstract Geologists and engineers study beaches from different points of view. The geologist is interested in present-day earth processes in part for the light they shed on ancient sedimentary rocks, and in part to understand the interplay of matter and energy on and within the earth.

Abstract The permanence of concrete in engineering structures is jeopardized where highalkali portland cement is used with aggregates containing opal, chalcedony, tridymite, intermediate to acidic volcanic rocks, or some phyllites. First recognized in 1938, deterioration caused by cement-aggregate reaction is characterized by cracking, expansion, and decline in strength and elasticity of the concrete. Petrographic and petrologic methods have contributed significantly to the investigation of cement-aggregate reaction. Microscopic criteria serve to distinguish between this and other types of deterioration. Petrographic examination of concrete aggregates can be used to predict their potential reactivity. Physical-chemical conditions contributing to the deterioration were explored by petrologic and geochemical methods. The mechanism by which reaction between rocks and minerals and the alkalies of cement causes this destruction is explained. Essentially i t consists of osmotic pressures produced by the formation and hydration of alkalic silica gels, which arise from interaction of alkalies and certain aggregates.

Abstract We are plagued by a definition. To the engineering enthusiast, Engineering Geology may mean aspects of geology that help the engineer, just as one of his many tools aids a carpenter. To the geological zealot, Geologic Engineering may mean aspects of geology that should control the planning and performance of work that is primarily engineering. I n the present discussion, both the use df engineering tools and methods by the geologist, and of geological facts and theory by the engineer, are classed as Geologic Engineering.

Abstract Many historical events from the earliest times have had a geological background, and the rapid progress made in industry by man has been based upon his discovery, development, and production of ores and the utilization of important metals or elements extracted therefrom.

Abstract During World War II geology won its spurs as an important scientific tool in both planning and operations by the United States Army. This growth of geology was due to increased appreciation on the part of our military leaders of the importance of scientific techniques and information, and to the increased appreciation on the part of our scientists of the usefulness of their abilities in the solution of a large variety of very practical problems. It can be fairly said that at the beginning of the war neither the military leaders nor the geologists fully appreciated the manifold applications of geology to military problems. Basically this was because the geologist, prior to the war, had signally failed to give sufficient thought to the many ways in which geology can and should contribute to solving everyday social and economic problems. I n engineering geology, for example, there were too few Berkeys.