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The dry weight composition of foodplants was estimated by a microscope technique for esophageal samples from steers, fecal samples of steers and fecal samples from sheep fed on the esophageal samples. Perennial species of foodplants forming more than 5% of the diets could be identified and quantified by the analysis of 100 microscope fields at 125 power magnification. The diagnostic features of fragile forbs were not as prominent in feces as they are in non-digested plants. Knowing what foodplants an animal eats was once a worthwhile research objective but now it is essential to also study "when" and "how much"

The chemical composition and dry matter digestibility of clipped plant species, total herbage, and actual and simulated cattle diets were studied on sandhill grassland in eastern Colorado during the growing season and after dormancy. Clipped plants declined in percent protein and digestibility and increased in other chemical components with advanced maturity. Marked differences in chemical composition were evident among species in early summer, but minimal by winter. Actual cattle diets and those simulated from hand clipped plants were similar in chemical and digestible dry matter composition during each sampling period. In early summer, cattle diets were considerably higher in quality than total herbage but this difference became progressively smaller later in the summer. During dormancy and after weathering chemical composition and dry matter digestibility of herbage and of the cattle diets were essentially the samk. Cattle grazing native grasslands select their diet from plants which are continually changing in chemical composition and digestibility. Because cattle prefer leaf tissue over stem tissue, young growth over old growth, and green material over dry material, their diet is generally higher in quality than total herbage available. In the present study, seasonal changes in chemical and botanical composition and changes in nylon bag dry matter digestibility of total herbage and of actual and simulated diets of cattle grazing sandhill grassland were determined. Chemical and digestibility changes which occurred in major forage species through the year were also studied. This paper is a part of a broad study in grassland nutrition; l A contribution from W-94 Regional Project on Range Livestock Nutrition. Scientific Series Paper No. 1632, Colorado Agricultural Experiment Station, Fort Collins. We thank D. N. Hyder, R. M. Hansen and G. M. Van Dyne for their suggestions in this research and K. L. Knox, C. L. Streeter and R. E. Bement for their constructive reviews of the manuscript.

Recent seismicity in Washington County, Ohio, has been suggested to be induced by wastewater disposal operations despite injection ~2 km above the Precambrian basement. We investigated the relationships between disposal well locations and operational histories, spatiotemporal patterns of seismicity enhanced by waveform correlation, and mapped subsurface structures. We also analyzed proxies for in situ stress conditions to evaluate existing principal stress orientations and magnitudes. Double‐difference relocations of small (ML ≤ 2.1) seismicity revealed linear clusters defining a NE‐SW orientation that parallels the trend of small‐amplitude folds in Upper Paleozoic rocks within 1–2 km of the injection well. Hypocenter depths of ~3.1 to 4.3 km indicate seismicity occurred along faults below the Silurian injection interval in lower Paleozoic strata and Precambrian crystalline basement. Similar folds/faults imaged in nearby seismic reflection lines were associated with basement‐involved fault systems that cut the injection interval targeted by the injection well, providing permeability pathways for fluid pressure increases that initiated slip. Interpreted faults were also optimally oriented in the regional stress field for reactivation due to injection‐related decreases in effective stress. Well completion records suggest that during the recorded seismicity, the Long Run‐1 well was injecting disposal fluids close to or above the fracture pressure of the targeted Silurian injection interval. A comparison of observed seismicity rates and monthly injection records from the disposal well also indicate a close correspondence between earthquake frequency and injection rate. Taken together, these results provide a physical framework for understanding why wastewater disposal operations induced the Washington County seismic sequence.

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