Landslide classification for identification of mud flows and other landslides
No abstract available.
Book chapter↗
Geology topics
D.A. Sangrey
Publications and source records attributed to D.A. Sangrey.
A nomogram for interpreting slope stability of fine-grained deposits in modern and ancient-marine environments.
Design of the nomogram is based on effective stress and combines consolidation theory as applicable to depositional environments with the infinite-slope model of slope-stability analysis. The link between the two combined theories is a term representing the effective overburden stress, which may be predicted from consolidation theory and a knowledge of sedimentation rate, time, and the coefficient of consolidation. In turn, if infinite-slope conditions are assumed to exist, the effective overburden stress can be used to derive a factor of safety against static slope failure by using the angle of internal friction and the slope angle. The nomogram applies to depostitional settings in which fine-grained sediment has accumulated at a relatively constant rate upon a base that is essentially impermeable. The model further assumes that the lateral extent of sediment affected by any mass movement will be great compared to its thickness and that no outside agents (e.g., cements, gas) are influencing the section. The nomogram is applicable to static conditions (inherent stability of the slope) and certain dynamic conditions (such as earthquakes). It may be used to investigate mass movements in the geologic past as well as those in modern environments.--Modified journal abstract.
Journal of Sedimentary Petrology↗
U.S. Geological Survey core drilling on the Atlantic shelf
The first broad program of scientific shallow drilling on the U.S. Atlantic continental shelf has delineated rocks of Pleistocene to Late Cretaceous age, including phosphoritic Miocene strata, widespread Eocene carbonate deposits that serve as reflective seismic markers, and several regional unconformities. Two sites, off Maryland and New Jersey, showed light hydrocarbon gases having affinity to mature petroleum. Pore fluid studies showed that relatively fresh to brackish water occurs beneath much of the Atlantic continental shelf, whereas increases in salinity off Georgia and beneath the Florida-Hatteras slope suggest buried evaporitic strata. The sediment cores showed engineering properties that range from good foundation strength to a potential for severe loss of strength through interaction between sediments and man-made structures.
Science↗
Report on laboratory testing of shallow sediments, Middle Atlantic Outer Continental Shelf
This report contains the results of geotechnical engineering testing on cores taken by the U.S. Geological Survey to evaluate the characteristics of the sea floor within the Baltimore Canyon Trough area. The coring took place in September, 1977 aboard the R/V ANNANDALE. During the cruise (AN-01-77), 20 vibracores were taken at 17 stations across the Continental Shelf off the coast of New Jersey (Figure 1). Table 1 shows the station locations, the water depths at each station, and the core lengths. The objective of the study was to obtain a set of representative index properties as well as strength and compressibility data on sediments from across the shelf in the Baltimore Canyon Trough area. It was anticipated that these data, although of a reconnaissance rather than a site-specific nature, would provide a useful indication of the engineering properties of these sediments. Ultimately, these data may be used for preliminary design applications and the assessment of potential hazards. In this report, the results are presented without any interpretation. An overall evaluation of all data collected during the study, including those contained in this report, presently is underway. Users of this report should be cautioned not to take these test results out of context. Two factors must be borne in mind. The first is that these tests were done on somewhat disturbed samples compared with those obtained through high-quality sampling programs onshore. Much disturbance is inevitable offshore but the significance of the disturbance on these test results has not yet been evaluated. The second factor is that these data are only part of the total set available from this project. A complete analysis of all data may lead to conclusions that are different from those based on this set of data only. The tests reported herein were performed by Geotechnical Engineers Inc., 1017 Main Street, Winchester, Massachusetts 01890, under Contract 14-08-0001-16232 of the U.S. Geological Survey. Richard Brown and Charles Osgood performed the engineering properties tests. Sally A. Wood of the U.S. Geological Survey handled the transfer of vibracores between the U.S. Geological Survey and Geotechnical Engineers Inc. and, also, assisted in the preparation of this report.
Open-File Report↗