We are funded through NSF to build one of three critical zone observatories designed to understand how weathering (both physical and chemical) and transport processes control the structure of the critical zone itself, and to explore the impact of the critical zone structure on hydrological, geochemical and biological functions. Our field site in the Boulder Creek watershed of central Colorado encompasses strong contrasts in erosional regimes, and therefore contains critical zone architectures that range from dominantly bare rock to deeply developed weathering profiles. We aim to exploit the natural experiment represented by these contrasts to examine the processes that shape the critical zone and the influence of the critical zone structure and character on hydrology and landscape evolution.

What is the critical zone?

The critical zone is the region where surface processes enact changes in the physical, chemical or biological character of rock. Consider the system from the point of view of a rock parcel as the surface lowers toward it, or in the Lagrangian reference frame, follow the rock as it moves toward the surface. The rock will initially have some set of physical and chemical properties set by the geological and tectonic history of the rock parcel. As it moves toward the surface, at a rate set by either the local erosion rate or the downward advance of the weathering front, processes driven by meteoric water, thermal fields, stress fields, or biological agents will begin to occur. As they do so they will produce changes in the rock properties that may catalyze feedbacks that drive further and faster change. Once the rock parcel “feels” the surface in this way, it has entered the critical zone. With further transformation, eventually the strength of the rock is insufficient to prevent disintegration, and particles are freed from their parent rock mass and can move independently. This is regolith, and the particle motions are now driven by a suite of processes ultimately slaved to gravity.

Graduate student positions

The Boulder Creek Critical Zone Observatory will have five fully funded graduate student positions, starting in the Summer and Fall of 2008, with research opportunities in all aspects of the CZO research. All interested students are encouraged contact appropriate researchers, and to apply though the appropriate academic departments geography, geology, and engineering at the University of Colorado, Boulder.

Boulder Creek CZO Proposal:

• Proposal summary
• Proposal text
• Review comments

Other CZOs

• Penn State
• Sierra Nevada