The Critical Zone. Earth’s permeable near-surface layer… from the tops of the trees to the bottom of the groundwater. It is a…

“The Critical Zone. Earth’s permeable near-surface layer… from the tops of the trees to the bottom of the 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.”

–Critical Zone Observatories, http://criticalzone.org/ (viainthenoosphere)