Observations on Seismic Waves Reflected at the Earth's Core Boundary
On the seismograms of many earthquakes the waves reflected from the outer boundary of the earth’s core oftentimes write traces which appear larger than the size of the shock warrants. A systematic study has been made of the displacement ratios of these core reflections to the direct body waves. Data accumulated during the course of this investigation tend to confirm the idea that the displacement ratios of the longitudinal waves reflected from the core to the longitudinal direct waves are greater than the presently accepted theory would indicate. Some possible causes of these differences are investigated, but reasonable changes in the assumptions do not result in an explanation of all of the discrepancy between the observed and theoretical data. Additional research projects are suggested that might help in answering some of the puzzling features of these phenomena.
Geology of the Manila-Linwood Area, Sweetwater County, Wyoming and Daggett County, Utah
The Manila-Linwood area, so named from the two Utah towns within its boundaries, consists of approximately 200 square miles lying on the Wyoming-Utah state border. It is interesting to the geologist from an historical,stratigraphical, or structural viewpoint.
Historically, this district is one of interest because it contains the famous Flaming Gorge, named by Major John Wesley Powell. It has been a locality for geological investigation by such men as Clarence King, S.F. Emmons, Ferdinand V. Hayden, and many others. A brief review of therecords of early geological and geographical explorations is presented.
Stratigraphically, one of the most completely exposed sections, representing a span of geologic time as long as or longer than that seen in any area of comparable size in the United States, characterizes the area. Rocks representing the Archean (?) and Algonkian eras, as well as all the later periods of the geologic time scale, with the possible exception of the Cambrian, Ordivician, Silurian, and Devonian, which are not differentiated into separate units in this report, are present in the district. These sedimentary rocks have been divided into 23 mapping units which are shown on a chart correlating them with the terminology used by previous workers in this area, and giving their tentative correlation with componentsused in adjacent areas. The character, thickness, age, and correlation of the various rock units are briefly discussed in the text. The only plutonic igneous bodies in the area are those intruded into formations of Archean (?) age. Extrusive accumulations are found at several places in the geologic column but are a very minor part of the section, consisting chiefly of tuffs interbedded in shales and sandstones. None of these igneous rocks were considered important enough to be designated as separate mapping units.
Structurally, the area embraces parts of two divisions of the Rocky Mountain province of the western United States. Its southern portion is a segment of the north flank of the great, east-west- oriented Uinta Mountain arch of northeastern Utah and its northern half is a sectorof the Bridger Basin of southwestern Wyoming. Superimposed on the north regional dip are minor, transverse flexures. A part of the much-discussed Uinta fault and other faulting of a rather complex nature are also found in the district. The structure is discussed in a chapter entitled"Structural Geology".
A brief history of the structural geology of the area is presented. A short chapter on the economic geology of the area, with an emphasis on the oil and gas possibilities is given.
Several problems worthy of further study in this and nearby areas are briefly discussed.
