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Science (mostly history, and mostly gravity)

Chasing the history of the gravity method sometimes took me down side-tracks that did not quite fit the theme, and so never made it into ‘The Hunt’. Also, and inevitably, there were stories that should have been in ‘The Hunt’ but which I missed. Here are some of them, and bits of new Earth Science are sometimes included!

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?

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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?

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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.

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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.

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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.

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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.

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In Memoriam – Hugh Davies

It is not given to many people to be recognised as the most important figure in the geological history of an entire country, but Hugh Davies, who died on April 26 this year, had that distinction.

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‘From Compass to Drone’ – a book review

In late 2022, Bill Hinze published, through the Minnesota Geological Survey, a book entitled From Compass to Drone: The Evolving Role of Magnetics in Mapping the Geology and Ore Deposits of the Lake Superior Region: 1830-2022.

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Tapping Jenny

Coincidentally, two recent threads on LinkedIn brought Assynt to mind. And one of those threads concerned Janet Watson, geological queen of the Northwest Highlands

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Float

In the instructions Joseph Gaimard copied into the diary before he left Toulon, there is a long section on field geology. Despite being written in 1817, it could very usefully be given as a guide to first-year geology students in our universities. Amongst other things, it has some very nice sketches and some wise words on the importance of context, but it also has comments on the importance of rocks that are not in situ

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