Simulation of pebble abrasion on coastal benches by transgressive waves

Tumbler simulations of abrasion processes affecting rocks on basaltic marine benches have clarified the effects of mass and volume of rock fragments on their rate of wear. Several experiments indicate that rate of basalt wear increases with mass in the interval 1 g to 8 g, but is not related to volume of fragments abraded in seawater. Relatively small quantities of rock flour suspended in the immersant seawater substantially reduced the rate of basalt wear. Basalt and calcareous beachrock responded differently in systems with both rock types tumbling together. Examination of the cuttings from these low-energy encounters suggests that abrasion on elevated benches along exposed seacoasts reduces virtually all clastic material to particles of silt size or smaller, producing essentially no sand.     

A statistical study of pressure changes in the troposphere and lower stratosphere after strong solar flares

Summary The average change in height of several constant pressure levels in the troposphere and lower stratosphere after a strong solar flare is described. The analysis covers the northern hemisphere north of 10°N and is based on a sample of 81 carefully selected flares from the period July 1957 through December 1959.The statistical significance of the results is tested by drawing a comparison with the results obtained when one applies exactly the same analysis to three samples of 81 random key-dates selected from the same period.Properties of the reaction pattern are (1) it is pronounced at high as well as low latitudes, (2) it consists of alternating cells of positive and negative height change, (3) it is established within six hours after the flare, and (4) the maximum response occurs near the tropopause.It appears more likely that the atmospheric reaction pattern can be attributed to very energetic solar particles rather than to enhanced ultraviolet radiation.     

The Application of Petroleum Hydrocarbon Fingerprint Characterization in Site Investigation and Remediation

Tremendous resources have been and continue to be spent investigating and remediating petroleum hydrocarbon compounds (PHCs) in soil and ground water. Investigating and planning a remedial strategy for sites affected by PHCs is often a challenging task because of the complex chemical nature of the PHCs. the complex regulatory environment related to PHC cleanup, and the use of analytical methods that provide quantitation but not identification of PHCs. From a technical standpoint, the PHC impacting soil and/or ground water is frequently inadequately characterised, both in identification as well as in is general properties (solubility, toxicity). From a regulatory standpoint, promulgated or recommended total petroleum hydrocarbon (TPH) cleanup levels generally relate to assumed properties of specific unweathered products and are inconsistent among different agencies and regions. This produces a prime situation for unwillingly spending more resources on investigation or remediation than may be necessary, especially when the PHC in the subsurface has different properties from unweathered products such as gasoline or diesel.
Accurately identifying the PHC and its nature, a process known as fingerprint characterization, is critical to the determination of appropriate regulatory goals and design of cost-effective remedial approaches. This paper presents several case studies in which fingerprint characterization made a significant difference in the project outcome. In each instance the nature of the organic material was better understood, the regulatory cleanup levels were negotiated based on the nature of the material, and a remedial approach was implemented that differed significantly from and was generally less costly than what would have been required without fingerprint characterization data.     

Secular changes,polarity epochs and tectonic movements as indicated by palaeomagnetic studies of Hungarian rock samples

Summary The paper contains an outline of the palaeomagnetic investigations in Hungary including some of their geophysical and geological applications. More than 500 samples of volcanic rocks were studied by usual palaeomagnetic techniques. The rocks investigated belong to three different geological periods — the Quaternary — upper Tertiary, the middle Miocene and the lower Cretaceous. The palaeomagnetic data obtained for the individual localities are summarized in the Appendix.Paper presented at the IAGA Symposium Madrid, September 1969.     

Minimizing structural vibrations with absorbers

In a companion paper¹ the authors show that the parameters of an absorber which will minimize the resonant response of a simple elastic body can be determined from known results by treating the body as an equivalent single degree-of-freedom system. In this paper cylindrical shells are considered as examples of dynamically complex structures, for which the ratio of the natural frequencies of adjacent modes tends towards unity. It is shown that as dynamic complexity increases optimum absorber parameters for the reduction of resonant response deviate increasingly from those for an equivalent single degree-of-freedom system. Absorbers can be used also to reduce the random response of structures. Simple expressions for optimum parameters are given for an undamped main system, which has one degree of freedom and is subjected to white noise excitation. Optimum absorber parameters for beams, plates and cylindrical shells show similar qualitative behaviour for random and harmonic response with the concept of an equivalent single degree-of-freedom system being applicable only for the simpler structures.     

Approaches indG/G-determinations

Summary Whereas observations of planets and solar satellites are more promising for detecting possible variations of Newtonian gravitational constant,G, with time the application of additional methods which are substantially different might be useful. It is discussed to what extent the tidal problems can be solved in connection with lunar orbit tracking for detectingG; further a relativeG-experiment at the earth surface is outlined.     

Reply to comments by K.A. Goettel and J.S. Lewis

Uranium has been measured by homogenized fission track analysis in 34 samples of 22 achondrites. Potassium has been determined in aliquots of eleven of these. The results, combined with previous Al data, are not compatible with achondrite formation from chondritic material by previously suggested fractional melting or metal-sulfide segregation processes.     

A NEW APPROACH TO MAGNETIC PROFILE INTERPRETATION*

By using two components of anomalous magnetic fields and a formulation including complex numbers it is possible to calculate the position parameters of thick plates and both magnetization and position of thin plates directly from any two or three points of anomaly profiles. The formulae (interpretation operators) allow automatic topographic corrections to be made. The new two-component operators give more reliable results than the conventional methods of interpretation. The variance of the parameter values obtained with subsequent points of an anomaly measures directly, the total error of interpretation. The application of infinite thin plate operators to a long profile results in characteristic patterns, from which the estimation of the number of plates and their approximate position is possible.