Geologic Life
A book with the title ‘Geologic Life’, and the subtitle ‘Inhuman Intimacies and the Geophysics of Race’ has recently given rise to a considerable amount of comment on LinkedIn. What, on Earth, is it all about?
An Iceland in the South Atlantic ?
The Rio Grande Rise Massif and the Valdivia Bank have been interpreted as the two halves of an originally continuous hot-spot-related plateau formed on the Mid Atlantic Ridge. Is Iceland an example of what that plateau might have been like, geologically at least, at the time of its formation?
Gravity and the Middle Amazon Basin
If it had not been for LinkedIn, I might never have been aware of the existence of the 2024 Bouguer gravity map of Brazil, and that would have been a pity. Some things jump out almost at first sight, and one of these is the narrow and almost linear gravity high that roughly coincides with the main course of the middle Amazon.
The D’Entrecaseaux Ridge: a southwest Pacific enigma
Free-air gravity maps suggest that, rather than having been a rectilinear feature, the subducted portion of the D’Entrecasteaux ridge, which impacts the Vanuatu Trench at a high angle, was curvilinear. The entire region is reminiscent, in size and the disposition of subduction -related volcanics and collision orogens, to the Banda Sea region of eastern Indonesia.
Gravity gradients – a beginning
Modern airborne gravity relies largely on measurements of gravity gradients. Given how very small the signal will inevitably be, it is clear that measuring it is bound to be very, very difficult. Nevertheless, it was being done in Australia in the late 1920s with some success.
The Imperial geophysicists
In the Preface to the report in the Imperial Geophysical Experimental Survey in Australia in the late 1920s and early 1930s, a few unforgettable names were listed. Attached to the survey was ‘J. M. Rayner, of the New South Wales Department of Mines’, and moving to the lower echelons, the Electrical Section had a field assistant called R. F. Thyer, while designated as a Temporary Assistant was one N.H Fisher.