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Northern peatlands are unique ecosystems typically located in boreal latitudes that sustain unique habitats and species. They are a critical component of the global carbon cycle, acting both as a carbon reservoir (via peat accumulation after sequestration of carbon dioxide from the atmosphere) and as a carbon source to the atmosphere (by releasing methane and carbon dioxide, two greenhouse gases produced by microbes that thrive in the conditions found in peatlands). Although the ecology of peatlands has been well studied for many decades, the geological controls on peatland development and groundwater flow patterns are not completely understood. In Maine (USA), peatlands began forming about 10,000 years ago following the retreat of the ice sheets at the end of the last ice age. They formed in depressions, often starting as lakes or wetlands, within the landscape carved by glaciers and draped with sediments. Almost two decades of research in several peatlands in Maine suggest that glacial landforms buried beneath peatlands may play a key role in regulating both the hydrology (including the presence of open water pools at the surface) and release of methane gasses from peatlands. Subsurface images using an array of hydrogeophysical methods (including ground-penetrating radar, GPR) constrained with direct coring has revealed the presence of buried esker complexes beneath (or close to) surface pools. Hydrological measurements further suggest that the presence of these permeable esker deposits (mainly gravel and sand) may enhance the connection of peatland water to underlying groundwater and help sustain these pools. Whereas geological maps show that the presence of esker systems in Maine are widespread, satellite-derived digital elevation models (DEMs) reveal that they are often proximal to peatland boundaries, further suggesting that they may commonly extend below the peat formation and control hydrology and carbon dynamics in more peatlands than previously thought. Better understanding of how the critical zone influences coupled water and carbon cycling in northern peatlands may improve the understanding of their contribution to radiative forcing of climate as the climate warms.