Volcaniclastic &
surface processes
Most volcanoes are positive landforms (with the exceptions of
maar craters and calderas) and therefore are subjected to the forces of
erosion. Only volcanoes that are
less than about 30 million years old still retain some remnant of their
original topography. This means
that volcanoes formed during the first 99% of Earth history are mainly recorded
as volcaniclastic components of sedimentary sequences or as remnants of the
intrusive plumbing of the volcanoes (such as plutons and dikes). Therefore, in terms of understanding
volcanism through most of the history of our planet it is essential to be able
to understand it through the filter of sedimentary processes.
The surface evolution of a volcano once it has finished
erupting can depend 
on a wide array of
processes. These include major
slope failures (debris avalanches), debris flows, creep, eolian and fluvial
processes, and in some cases glacial processes. Some of these can be hazardous to surrounding populations
even when the volcano itself is dormant or extinct. And, the non-eruptive volcaniclastic sediments (i.e.,
sediments composed of volcanic fragments but not directly emplaced by a
volcanic process like a pyroclastic
deposit) at a volcano or volcanic region can provide key information
on eruptive history if the primary eruptive deposits have been completely
remobilized by sedimentary processes.
My current interests in this area are focused on surface
processes on volcanic landforms in arid regions. Recent studies have shown that the rate and type of surface
processes in these settings are very sensitive to the initial characteristics
of the volcanic deposit (including both pyroclastic deposits and lavas). Previously, different stages and types
of soil development or erosion on volcanic surfaces were interpreted in terms
of different ages, leading to the erroneous conclusion that some ndividual
scoria cone volcanoes in the western U.S.A. had erupted over many tens of
thousands of years. Rather, the
fact that a monogenetic volcano, which is an instantaneous event in terms of
geologic time, can produce different types of initial surfaces provides an
excellent opportunity to define the effects of those initial properties on
surface processes. There is also
potential for feedback to volcanology in situations where a volcanic landform
is highly degraded but where the surface morphology could give insight into the
original eruptive facies. This
topic of research is complementary to my overall interests in basaltic volcanic
fields in arid regions (see Basaltic
volcanism).