Dr Carolyn Boulton is a structural geologist at Victoria University of Wellington and she sees things in rocks that most of us would never notice. Including finding beauty in greywacke, which is a common, rather ordinary grey rock that most geologists would regard as somewhat dull.
Carolyn’s real passion, however, is earthquakes and the way faults – and greywacke faults in particular – behave.
Dr. Carolyn Boulton next to the slipping zone on part of the Wellington Fault Photo: Alison Ballance
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A fault is a sliding zone, where two blocks of rock slip past one another during an earthquake. That slipping is often lubricated by fault gouge, a fine-grained clay-like substance that is created by the grinding pressure of the rocks on either side.
Carolyn has become an expert fault hunter, reading the landscape for clues about its past. Last winter she noticed that big floods in the Hutt River had washed away a thick layer of gravels to reveal a new exposure of the Wellington Fault. She has been returning to the site to study it and collect samples of the fault gouge. She will study these small samples in overseas labs under high temperature and pressure, like those experienced within the fault itself, and she hopes the data will shed new light on why faults sometimes slide and sometimes stick.