摘要:

Several models are necessary for the study of the rotation of the Earth during its whole evolution. For the fluid state we adopt a zonal rotation with angular velocity increasing from the poles to the equator. After the formation of the Earth's crust the zonal currents in the core seem to have very important influence on the formation of the continents and mountain building. A certain “mean” rotation of the crust about the same axis can be explained by their action. But there are two factors more: the asymmetry of the distribution of masses in the crust and the ceaseless adaptation of the whole Earth to figures of equilibrium corresponding to different positions of the axis of rotation (for this model there are three axes of rotation to be defined). The migration of the poles seems to be explained by a theorem of Milankovitch. The path of the North Pole, for example, since the Silurian may be represented by parts of three paths corresponding: to a single continental block, to an intermediate state, and to the present distribution of contine

ISSN:0002-8606    

DOI:10.1029/TR030i006p00797

年代:1949

数据来源: WILEY

摘要:

The flow of an incompressible and homogeneous (autobarotropic) atmosphere in a steady frictionless state is considered. In Part 1, the equations are set up for an air flow of finite width with fixed lateral boundaries. The final equation which is non‐linear with non‐constant coefficients is integrated by a graphical step by step procedure. The horizontal streamline pattern is obtained along with the pressure profile through the central portion of the field. A pressure trough is found to the lee of the mountain. In Part 2, the equations are set up for an air flow of infinite lateral extent. The final equation is integrated by a numerical step by step procedure. The position and the intensity of the lee pressure trough is found to depend on magnitude and direction of the initial air current and on the size and shape of the mountain. Finally using an idealized Rocky Mountain profile, the lee pressure trough is found to be in the vicinity of 90–100°W longitude depending on the initial wind velocity, which is in agreement with observationa

ISSN:0002-8606    

DOI:10.1029/TR030i006p00818

年代:1949

数据来源: WILEY

摘要:

A magnetic model study of Bikini indicates that basement material rises to within 5000 ft of sea level approximately one mile to the northeast of Bikini Island. The model assumes uniform susceptibility and zero permanent magnetization and conforms to known seismic profiles of the basement.

ISSN:0002-8606    

DOI:10.1029/TR030i006p00831

年代:1949

数据来源: WILEY

摘要:

The airborne magnetometer AN/ASQ‐3A has been modified and auxiliary equipment has been developed to meet requirements for constructing isomagnetic contours of the total magnetic field over extensive areas for use in magnetic prospecting. The principal features of the instrument system are: (a) a self‐oriented magnetometer which utilizes the output of a system of saturable inductors to provide a d‐c response of low noise level and drift rate; (b) instruments for aiding the pilot to follow predetermined lines of a grid or network covering the area to be explored; and (c) an interlocked group of recorders for automatically correlating a continuous magnetometer record with plane position and altitude.The system described has been used extensively by the United States Geological Survey, the United States Naval Petroleum Reserves, and the United States Naval Ordnance Laboratory in aerial magnetic exploration under a wide variety of conditions. Similar systems are also being used by a few commercial comp

ISSN:0002-8606    

DOI:10.1029/TR030i006p00836

年代:1949

数据来源: WILEY

摘要:

Irregular oscillations of the near‐shore water level, with periods of the order of several minutes, are correlated with fluctuations in the height and period of incoming wave

ISSN:0002-8606    

DOI:10.1029/TR030i006p00849

年代:1949

数据来源: WILEY

摘要:

Wave action is a major factor in the formation of beaches and major shore features. However, there are sedimentary formations apparently having their origin in shallow seas in the absence of wave action. This could occur if the bed sloped upward very gently from a moderate depth to the shore line so that the waves approaching the shore were gradually modified in shape and energy content, arriving with zero energy and without breaking anywhere. A mathematical analysis of the problem is made on the assumption that the slope of the bed is such that the waves move shoreward with their maximum possible height without breaking. The bed profile which will accomplish this is computed, and the geological implications of the theory are presented

ISSN:0002-8606    

DOI:10.1029/TR030i006p00855

年代:1949

数据来源: WILEY

摘要:

The late Tertiary volcanism in the San Juan Mountains of southwestern Colorado followed a long interval during which the crust was stable. The volcanic rocks have been divided into four main groups, (1) those of pre‐Potosi (?) age in the eastern area, (2) the Lake Fork quartz latite, San Juan tuff, and Silverton volcanic series, (3) the Potosi volcanic series and the Fischer quartz latite, and (4) the Hinsdale formation separated by long intervals without eruptions. Each of the groups is made up of rocks from basalt to rhyolite with chemical and other peculiarities. During the eruption of a group there was little deformation but there was subsidence after the eruption of two of the groups and doming after the eruption of the last group.The magma moved into the area from the sides and was erupted about as rapidly as it moved.in. For the group named the Potosi volcanic series, the first eruptions had a composition near that of the primary magma ‐ dark quartz latites. Their eruption was followed by a short time without eruptions during which the magma became layered by crystal settling. The next eruptions were rhyolites followed abruptly, probably because of active movement of magna by dark quartz latites. The process was repeated three times.Subsidence caused by withdrawal of magma followed, and after a long time a new and different magma moved into the area and yielded the rocks of the Hinsdale formation. After the Hinsdale, a magma intruded the area with subsequent doming, but without erupti

ISSN:0002-8606    

DOI:10.1029/TR030i006p00862

年代:1949

数据来源: WILEY

摘要:

The measurement of the radioactivity of 136 rock samples within and around the Round Lake batholith near Kirkland Lake, Ontario, shows a regular increase in radioactivity from south to north. This is believed to be due to the northward plunge of the batholith and the migration of radioactive elements towards the top surface. This agrees with previous work by Keevil and Ingham on other batholiths.This evidence of the rise of radioactive elements suggests that the radioactivity of the crust as a whole may be much less than that determined from samples taken on its surface. Using values for the lower part of the batholith as representative of the granitic layer it is estimated that at Kirkland Lake 40 per cent of the total heat flow from the interior of the Earth may be accounted for by the radioactivity of the rocks in the top 36 km of the crust.It is also assumed that erosion has removed the more highly radioactive material from the Earth's surface and deposited it as sedimentary, heat‐producing shelves or dumps along the edges of the continents. These dumps may have determined the location and their heat may have assisted in the formation of marginal mountain range

ISSN:0002-8606    

DOI:10.1029/TR030i006p00867

年代:1949

数据来源: WILEY

摘要:

The distinction is drawn between smooth and rough channel flow, and formulas developed giving Chezy's constant for smooth channels in terms of the Reynolds number, for non‐turbulent and ultra‐rapid f

ISSN:0002-8606    

DOI:10.1029/TR030i006p00875

年代:1949

数据来源: WILEY

摘要:

Flood data are ordinarily listed either in annual‐flood series or in a partial‐duration series. If the expectancy of a flood in the duration series ϵ is known, then the probability of that flood being an annual flood is shown to be e−ϵ. From this relationship it is possible to transform recurrence intervals in the partial duration series to those in the annual‐flood series. It is shown that for equivalent floods, the recurrence intervals in the partial‐duration series are smaller than in the annual‐flood series, but that the difference becomes inconsequential for floods greater than about five‐year recu

ISSN:0002-8606    

DOI:10.1029/TR030i006p00879

年代:1949

数据来源: WILEY