ARCHIVED CONTENT: In December 2020, the CZO program was succeeded by the Critical Zone Collaborative Network (CZ Net) ×

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We are an NSF-supported environmental observatory focused on the "Critical Zone": where water, atmosphere, ecosystems, and soils interact and shape the Earth's surface.

The Boulder Creek Critical Zone Observatory is based at the University of Colorado at Boulder and founded in 2007. About 40 people are closely involved in our research, including about 10 graduate students and 10 undergraduates. As part of the National CZO Program, we serve the international scientific community through research, infrastructure, data, and models.

What is the Critical Zone?... Where rock meets life!

The Critical Zone is Earth's porous near-surface layer, from the tops of the trees down to the deepest groundwater. It is a living, breathing, constantly evolving boundary layer where rock, soil, water, air, and living organisms interact. These complex interactions regulate the natural habitat and determine the availability of life-sustaining resources, including our food production and water quality.

The critical zone is poorly understood:

  • How does it form?
  • How does it function?
  • How will change in the future?
  • More specifically, too little is known about how physical, chemical, and biological processes in the Critical Zone are coupled and at what spatial and temporal scales. Many of these processes are highly nonlinear and can range across scales from atomic to global and from seconds to aeons.

How will the Critical Zone respond to changing climate & land use?

Together with our counterpart observatories, Boulder Creek CZO is advancing our understanding of the Critical Zone. In particular, we are working collectively to develop a robust predictive ability for how the structure and function of the Critical Zone evolves and how it will respond to projected climate and land-use changes. This effort requires a systems approach across a broad array of spatial scales, timescales, and scientific disciplines, including hydrology, geology, soil science, biology, ecology, geochemistry, and geomorphology. And it requires advances in

  • theory
  • modeling
  • measurement

Together, the National CZO program has plans for the next decade that will produce a fundamental understanding and data sets that will stimulate, inspire, and test the resulting predictive models.

How does erosion and weathering control Critical Zone architecture and evolution?
The six Critical Zone Observatories work closely together on overarching science questions but also focus on aspects of Critical Zone science that fit the strengths of its investigators and its physical setting. Boulder Creek CZO specializes in erosion and weathering processes, concentrating on slope, climate, ecosystems, and rock properties.

Support and Partners

Our research and infrastructure are supported by the US National Science Foundation, Geoscience Directorate, Earth Science Division.

Our field sites are on City of Boulder land, Boulder County Open Space, and U.S. Forest Service land, and share some overlap with the Niwot Ridge Long-Term Ecological Research (LTER) site, and the Southern Rockies-Colorado Plateau domain of the National Ecological Observation Network (NEON),


Boulder Creek CZO

Boulder Creek Critical Zone Observatory

Boulder Creek CZO

Established 2007

"We study how erosion and weathering control Critical Zone architecture and evolution, concentrating on slope, climate, ecosystems, and rock properties."

Science Questions:

  • What is the legacy of climate and geologic history in critical zone architecture?
  • How are the dynamics of key interfaces within critical zone governed?
  • What are the feedbacks between hydrologic and ecological processes and critical zone evolution?
  • How do landscape position, slope aspect, microclimate and rock properties control the evolution of the critical zone?

Our CZO spans from the Continental Divide (4120 m) in the Front Range of the Rockies to the western edge of the Plains (1480 m).

Our research takes advantage of large differences in elevation, climate, geologic history, and weathering regime.