Z-trend maps for quick recognition of geologic patterns

Z-trend maps are a simplified lineprinter version of spatially filtered maps designed to give a quick visual appraisal of trends. The printout shows a yes-no configuration by a printed character or a blank so that the map has a conspicuous pattern. This pattern reflects the presence, position, and trend of the desired features. If a reasonable symbol density ratio is used the results can be visually pleasing thus enhancing trend recognition. Z-trending can be adapted to any map with stationary properties but is most easily applied to data that have been filtered with a bandpass operator.     

An investigation of dispersive effects on tidal gravity measurements at Alice Springs

A year-long record of tidal gravity has been analysed with the intention of detecting the increase in amplitude of the semidiurnal and diurnal waves by physical dispersion. The effect was found to be too small, even for the most extreme models, to be detected with present techniques. This is partly because of instrumental limitations and partly because of the nature of the calibration of the instruments.It is suggested that the best way to observe the effects of physical dispersion may be through changes in day-length at semi-monthly and monthly periods.