Deciphering or modeling rocks deformed under transient conditions—for example, in the brittle-ductile transition zone—is complicated by a lack of understanding of non steady-state deformation. In collaboration with Greg Hirth at Brown University I’ve been investigating the role of transient stress states on the microstructural development of quartz under both increasing and decreasing stress. The results quantify rates of grain growth and grain size reduction during deformation and provide textural guidelines for interpreting deformation history in structurally sophisticated rocks. The above figure compares our results (circles) to the predictions of a grain size-stress relationship known as the paleowattmeter (lines).