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Humbling hindsight

Bryan Lovell provides a retrospective on the Eocene Tyee Formation of the Oregon Coast Range

24 June 2024

Castle Peak of the Idaho Batholith, USA. Back in 1969, a contribution to the Tyee sandstones of Oregon’s Coast Range from the now distant Idaho Batholith seemed implausible. Now Bryan feels he missed an early chance to make a sedimentological contribution to a contemporary revolution in geology – plate tectonics. (Image credit: Leaflet, CC BY-SA 4.0, https://creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons)

In the summer edition, our President Jon Gluyas describes how a youthful essay on meteorite geochemistry and the geology of the Solar System was shown to be wrong (Geoscientist 34(2), 20-21, 2024). His ideas were contradicted by observations made on subsequent planetary missions. Fellows of the Society might ask: “What did I get wrong in my own early studies?”

From 1964 to 1968, I was a PhD student at Harvard University. My research was on the sandstones of the Eocene Tyee Formation in the Oregon Coast Range (Lovell, 1969a, 1969b). My interpretation of the deposition of these rocks now looks rather too simple (Santra et al., 2013). That is just one humbling hindsight: there is another.

The mineralogy of the Tyee sandstones that I collected in the Coast Range (Lovell, 1969a) largely supported the established idea of provenance from the Klamath Mountains to the south. The Klamath source was also indicated by northward changes in facies in the Tyee. But there was some evidence in my results of additional supply of sand from a plutonic source not present in the Klamath Mountains (Rogers, 1989). A contribution from a now-distant plutonic source such as the Idaho batholith was implausible – unless one applied the new thinking on tectonics to understanding the geology of the western USA (e.g. Hamilton & Myers, 1965).

By 1968 I had achieved my main objective: a study of proximality in turbidites that avoided circular reasoning. I wanted to complete my PhD in good time to catch the boat back to Europe, so in writing-up I decided to avoid any delay that might be caused by embroilment in the fierce contemporary debate at Harvard on plate tectonics. That might have been a reasonable tactical move in 1968, but I should have picked up the issue soon afterwards. My reply to a discussion of Lovell (1989a) by Rogers (1989) now looks inadequate: a missed opportunity.

It turned out that the mineralogical anomaly in the Tyee sandstones could be understood in the light of paleomagnetic evidence of post-depositional clockwise rotation of the Tyee Formation presented by Simpson and Cox (1977), later supported by Heller and others (1985). Provenance of some Tyee sands from the Idaho batholith came into play.

On the strength of my own petrographic findings, I could have published plausible speculation on such large-scale tectonics. With hindsight, I was too cautious. I had missed an early chance to make a sedimentological contribution to the contemporary revolution in geology.

Author

Dr Bryan Lovell

Emeritus Senior Researcher in Earth Sciences, University of Cambridge, and President of the Geological Society of London 2010 – 2012.

Further reading 

 

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