UCL Science Society meeting - Professor James Croll - 24 October 2017
Oct 24, 2017 05:30 PM
End: Oct 24, 2017 08:00 PM
Title: "How might Gower Street pavement failures help explain some fundamental problems of geology?"
Speaker: Professor James Croll (UCL) - Department of Civil, Environ & Geomatic Engineering (research profile)
Venue: Gordon Square (25) 107 (map)
Abstract: Triggered by an attempt almost two decades ago to explain the emergence of fields of curious blisters on newly laid asphalt pavements outside my office on Gower Street, I soon found myself exploring the possibility that similar mechanics could be at work in the formation of a number of curious and imperfectly understood geomorphic features in permafrost and periglacial environments – albeit at different orders of magnitude of temporal and spatial scales. Contrary to conventional wisdom all in one way or another appear to involve cyclic heating and cooling in which the accompanying fluctuations of compression and tension loading, arising from the restraints to expansion and contraction, result in the non-recoverable deformation failures that define these geomorphic features. Recent images from space probes show very similar features on some of the outer planets and their satellites. All appear to involve one or other form of thermal ratchet failures.
Driven by the conviction that very similar thermal mechanics could be at work in the motion of glaciers and ice sheets, along with some very curious familial happenstance, more recent work has focused on whether glacial and interglacial cycles of thermal loading at 20 -100ka periodicity occurring within the cycles of hot-house and ice-age periodicities of circa 120Ma, related mechanics could be helping to shape the Earth’s crust. Some of the geological evidence seemingly at odds with the predictions of the current ruling geological paradigm of plate tectonics will be reviewed and an alternative model relying upon these very long term cycles of thermal loading will be briefly outlined. It will be suggested that the evolution of the Earth’s crust might have closer links to the formation of Gower Street blisters than it does to the boiling of a bowl of porridge.