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In humid environments surface water erosion, rather than seepage water erosion has been considered the major erosional force. The canyons in Starved Rock State Park, north-central Illinois, are not typical in form for eastern United States humid-temperate climate landscapes. In and around Starved Rock State Park the valley cross-profiles are box shaped rather than "V"-shaped with amphitheater heads, steep walls and broad valley bottoms. Other large and small-scale features of the canyons are also largely indicative of seepage erosion.Using field data it was determined that active canyon headwall erosion was occurring in the park at a rate of approximately 0.02 m/year. This is in fact the rate that would be needed to erode the canyons to their current length, showing that seepage erosion, the dominant erosional force in the park, is indeed capable of erosion rates necessary to entirely form the canyons within Starved Rock State Park. / Department of Geology

Indiana University-Purdue University Indianapolis (IUPUI) / Deep injection of waste CO2 and fluids from regional energy plants into the St. Peter Formation of the Illinois Basin, could effectively provide long term deep geologic storage. This research aims to explore the viability of this proposed injection. There are some basic criteria that must be met to effectively store waste in a geologic reservoir. First, the reservoir must have sufficient porosity and permeability for both injectivity and for migration of the injected fluid through the reservoir. Second, the reservoir must be overlain by some form of impermeable seal or cap layer(s). Third, the reservoir should be sufficiently isolated from interaction with surface and near surface water. Finally, the formation must contain enough storage volume to handle significant amounts of injected material. Massive sandstone formations that host large saline aquifers have the potential to serve as high capacity storage sites. Much of the research targeting the potential suitability and storage capacity attributes of these formations has been promising, but reproducibility of the results has been less than ideal. Some of this variability has been attributed to petrological differences in the sandstone reservoirs that are not readily evident when studying the target formation over a geographically significant area. Based on the criteria, a promising candidate for injection and storage is the St. Peter Sandstone of the Illinois Basin. This study investigates the viability of liquefied CO2 storage within the St. Peter Sandstone on a micro scale. Initial porosity and permeability of the formation plug samples ranged from 16% to 19% and 26 to 981 millidarcies (mD), respectively. The wide difference in permeability is attributed to variations in strength of the cement, in this case quartz overgrowth in the sandstone. This preliminary evidence indicates that the storage capacity of the formation will remain constant or increase depending on injection location, suggesting that the St. Peter Formation will lend itself well to future storage.